Multi-state power management for computer systems

ABSTRACT

A power conservation system for use in a computer system. The power conservation system has an activity mointor and a plurality of modes of operation. By controlling the power mode of operation in response to the activity of the computer system, the power consumption of the computer system is controlled. Coupling of circuit power and clock signals are used to control power consumption and both hardware and software components may separately or together monitor and control operation.

CROSS REFERENCE RELATED U.S. PATENT APPLICATION

This application is a continuation of application Ser. No. 08/285,169 filed Aug. 3, 1994, now abandoned, which is a continuation of application Ser. No. 08/017,975 filed Feb. 12, 1993 now U.S. Pat. No. 5,396,635, which is a continuation of application Ser. No. 07/908,533 filed Jun. 29, 1992, now abandoned which is a continuation of application Ser. No. 07/532,314 filed Jun. 1, 1990, now abandoned.

BACKGROUND OF THE INVENTION

A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.

The present invention relates to computers and particularly to methods and apparatus for power management in computers, particularly in battery-powered computers.

The major parts of computers include a central processing unit (CPU), input/output (I/O) devices such as display screens, keyboards, modems, printers, disk drives and the like, and storage (memory).

The CPU communicates with the I/O devices, with the storage and otherwise operates with addresses defined within the computer address range. Typically, addresses for I/O devices are within an I/O address range. Addresses for execution of programs without I/O reference typically are within a memory address range. Similarly, that portion of memory allocated for display is within a video memory address range.

Computers function to execute application programs such as word processing, spreadsheet and data base management programs. Typically, the computer and the application programs are under the control of a software operating system that manages the different system parts and resources including some I/O devices. For example, during the execution of an application program when the CPU wishes to check to determine if any key has been depressed on the keyboard, the CPU through a subroutine call to the operating system requests the operating system through execution of a subroutine to perform a key-actuation detection task. Since the operating system performs many such tasks, the operating system has a detailed knowledge of many activities within the computer. However, under some circumstances, application programs bypass the operating system and directly address I/O devices. Typically, each I/O device is assigned an I/O address within an I/O address range. For application programs which directly address I/O devices without operating system calls, the operating system is not immediately aware of I/O activity. With such complex operation in computers, the task of power conservation is difficult.

The need for power conservation is well known in battery-powered computers and must be performed in a manner that does not interfere with the operation of the computer or impede users from interacting with the computer during the execution of application programs.

Conservation of power has been utilized for some parts of battery-powered computers but has been ignored for other parts of such computers. In general, power consumption is distributed in battery-powered computers among the major parts of those computers. One part with significant power consumption is the central processing unit (CPU). Another part is the input/output (I/O) devices such as display screens, keyboards, modems, printers, disk drives and the like. Still another part with significant power consumption is storage (memory).

Prior art attempts at conserving power have employed screen blanking which reduces the power to the display screen when the screen has not been used for some period of time. Typically, a timeout circuit senses changes in screen information and, if no change has occurred for a predetermined timeout period, the backlight to the screen is turned off for power reduction. While screen blanking is effective in reducing power for the display screen, no reduction results in power to the driver circuitry for the display, to the CPU, or to other parts of the computer. Furthermore, when the screen is blanked, the computer cannot be used until reset.

Other prior art attempts at conserving power consumption have focused on disk drives because the power consumption of rotating magnetic disks is high. Disk drive manufacturers have employed various schemes for reducing the power consumption of the disk drive. While such power consumption schemes are effective for the disk drive, no reduction results in power to the CPU or other parts of the computer. Computers without disk drives, such as small "notebook" computers, have no need, of course, for the conservation of power in a disk drive.

In order to extend the battery life of portable computers and to manage power in computers, there is a need for improved power management methods and apparatus in computers, particularly for power management that can be extended to many different parts and conditions of the computer.

SUMMARY OF THE INVENTION

The present invention is a method and apparatus for power management in a computer. The computer typically includes as hardware a central processing unit (CPU), storage (memory) and I/O devices and includes as software an operating system adapted to control the computer during application program execution.

The power management method and apparatus causes the computer system to enter the power conservation mode after sensing inactivity by a software monitor or by a hardware monitor.

The software monitor monitors the activity of the operating system or other software in the system. The software monitor typically is a software module linked, for example, to the operating system at boot time for monitoring subroutine calls to the operating system.

The hardware monitor monitors the hardware to detect inactivity. The hardware monitor typically is circuitry for detecting inactivity independently from the software. For example, the hardware monitor senses predetermined address ranges, such as an I/O address range and a video memory address range, and monitors the activity of addresses by the CPU to addresses within these ranges. If no data transfers occur within the specified address ranges for predetermined periods of time, then a power conservation mode is entered to conserve power in the computer system.

By using both a software monitor and a hardware monitor, the power management unit determines exactly when to enter into power conservation mode without sacrificing system performance.

In the software monitor, inactivity is determined by detecting how many "active" or "idle" function calls an application makes within some time period. In the IBM PC DOS environment, the activity status is checked, for example, no less frequently than every 50 milliseconds. There are 256 IBM PC DOS function calls and, in principle, each is labeled as "idle" or "active" and each is assigned a corresponding positive or negative number. A positive number is assigned to an "active" function call and a negative number to an "idle" function call.

The power management software monitor forms an activity measurement as a running total of the function call numbers as the function calls are made. Whenever a function call is made (either active or conservation), the power management software monitor algebraically adds the function call number to the accumulated value and determines whether the system is to remain in the active mode or be switched to the conservation mode by comparing the magnitude of the accumulated value with a function call threshold.

The function call threshold for determining activity is a variable depending on the computer system speed. To prevent the system from oscillating between the active and conservation mode due to minor changes in system activity, hysterisis is provided by using active and conservation function call thresholds. The accumulated total for the activity measurement is reset after it reaches the active threshold going in one direction or the conservation threshold going in the opposite direction as the case may be.

The active and conservation thresholds are typically unequal so that the entry and exit from conservation mode is biased. For example, in order to have the system enter the conservation mode quickly and thereby to reduce power consumption, the active threshold is set with a number greater than the number for the conservation threshold.

In one embodiment, functions that require immediate attention are assigned numbers large relative to the active and idle thresholds so that a single occurrence of the function call will force the accumulated count over the active threshold and thus force the system to be in the active mode. The hysterisis effect can be bypassed by forcing the power management unit into active mode without changing the activity count. In this case, the next idle function call will bring the system back to idle mode.

If the software monitor or the hardware monitor indicates inactivity, the power management unit enters the conservation mode. The conservation mode has multiple states which provide different levels of power conservation.

A first state, called a DOZE state, is entered after sensing inactivity by the hardware monitor for a first period of time. A second state, called a SLEEP state, is entered after sensing inactivity by the hardware monitor for a second predetermined time where the second predetermined time is greater than the first predetermined time. A third state, called a SUSPEND state, is entered after sensing inactivity by the hardware monitor for a third period of time greater than the first and second time periods.

Another state is OFF which turns off all power for the computer under predetermined conditions.

During periods of inactivity, power consumption is reduced in different ways, for example, by reducing clock speeds or removing clocks, and/or by removing power, and/or by controlling the refresh frequency to memory.

In accordance with the above summary, the present invention achieves the objective of providing an improved power management method and apparatus.

The foregoing and other objects, features and advantages of the invention will be apparent from the following detailed description in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a block diagram of a computer with the power management unit of the present invention.

FIG. 2 depicts a block diagram of the power management unit of the FIG. 1 system.

FIG. 3 depicts a detailed block diagram of the hardware for the power management unit of FIG. 2.

FIG. 4 depicts a state diagram depicting the multiple states associated with the power management unit of FIGS. 1, 2 and 3 as determined by the hardware monitor.

FIG. 5 depicts a representation of operation for various states as a function of the activity measurement.

FIG. 6 depicts a state diagram depicting switching to conservation mode (DOZE or SLEEP state) operation under control of the software monitor.

FIG. 7 depicts a state diagram depicting the sequencing which forces to the ON state during an activity window period under control of the software monitor.

FIG. 8 depicts a representation of operation for a spreadsheet application program.

FIG. 9 depicts a representation of operation for a word-processing application program.

FIG. 10 depicts a representation of operation for a windowing application program.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Computer System--FIG. 1

In FIG. 1, computer 3 is typically a small, battery-powered computer such as a "notebook" computer. The computer 3 includes a CPU 4, a CPU bus 5, a plurality of I/O controllers 6-0, . . . , 6-n where "n" is a constant equal, for example, to 7. Connected to the controllers 6-0 through 6-n are plurality of peripheral devices 7-0, . . . , 7-n, respectively. The controllers and peripheral devices 6 and 7 typically include a keyboard, a display, a hard disk drive, a modem, a printer, and similar devices. Each of the controllers 6-0 through 6-n connects to the conventional computer bus 5.

Also connected to the bus 5 is the memory, which in one particular embodiment is DRAM random access memory 11. The memory 11, when of the type requiring refresh, is refreshed with *RAS and *CAS lines 29 under control of the PC controller 13 which provides *PCRAS and *PCCAS signals on lines 30 to power management unit 15 including a hardware monitor 79 and a software monitor 80. The I/O devices are separately powered through switch unit 22 and switches 22-0, . . . , 22-n by the VCC power from power supply 9 which receives power either from the battery 10 or an AC source 14. Power supply 9 is of a conventional type which supplies a low battery signal LB, a low-low battery signal LLB, and an AC power signal ACPWR to power management unit 15.

The computer 3 typically includes as software an operating system adapted to control the computer system and to control operations during application program execution. Computer 3 functions to execute application programs such as word processing, spreadsheet and data base management programs. Computer 3, during the execution of application programs, is under control of a software operating system. The operating system manages the different system parts and resources including the I/O devices 6 and 7. For example, during the execution of an application program when the CPU wishes to check to determine if any key has been depressed on a keyboard I/O device, the CPU 4 through a subroutine call to the operating system requests the operating system to execute a subroutine to perform a key-actuation detection task. Since the operating system performs many similar calls to the operating system, these calls represent detailed information about many activities within the computer system.

In FIG. 1, the computer 3, through the CPU 4, issues control and address signals on the bus 5 which define the overall computer address range for computers including the sets of address ranges for all of the memory, I/O and other devices connected to the bus 5. Whenever any of the peripherals 7-0 to 7-n are to be accessed for data to be transferred over the bus 5, the address of the corresponding I/O controller 6-0 to 6-n (either by unique address lines or unique address lines in combination with control lines) specifies the addressed one of the I/O controllers 6 and corresponding peripheral 7.

Similarly, memory 11 has locations addressed by a set of addresses on bus 5 within a memory address range. Some of the addresses in the range of addresses for memory 11 are typically allocated and reserved only as a set of video memory addresses. Whenever the video memory region 8 of memory 11 is to be addressed, address appears on bus 5 within the set of video memory addresses.

The computer system of FIG. 1 includes a power management unit 15 having a software monitor 80 and a hardware monitor 79 for monitoring activity of the computer system. The power management unit 15 is connected to the bus 5 to sense activity, using hardware monitor 79, on the bus 5 and is connected to the CPU 4 (executing the operating system and the software monitor 80), the power supply 9, the memory 11 and PC controller 13 for controlling power management.

The power management unit 15 of FIG. 1 operates to cause the computer system to enter the power conservation mode after sensing inactivity by the hardware monitor 79 or by the software monitor 80 and to enter the active mode after sensing activity or other conditions.

The hardware monitor 79 monitors the hardware to detect inactivity. The hardware monitor 79 typically is circuitry for detecting inactivity independently from the software and the software monitor 80. For example, the hardware monitor 79 senses predetermined address ranges, such as an I/O address range and a video memory address range, and monitors the activity of addresses by the CPU to addresses within these ranges. If no data transfers occur within the specified address ranges for predetermined periods of time, then a power control mode is entered to conserve power in the computer system.

The software monitor 80 monitors the activity of the operating system or other software in the system. The software monitor 80 typically is a software module linked, for example, to the operating system at boot time for monitoring subroutine calls to the operating system.

By using a software monitor 80 and a hardware monitor 79, the power management unit 15 decides exactly when to enter into power conservation mode and active mode without unnecessarily sacrificing system performance.

The power conservation mode includes a number of activity states. A first state, called a DOZE state, is entered after sensing inactivity for a first period of time by the hardware monitor or when an idle threshold is exceeded as determined by the software monitor. A second state, called a SLEEP state, is entered after sensing inactivity by the hardware monitor for a second predetermined time where the second predetermined time is greater than the first predetermined time or when the activity measurement sensed by the software monitor exceeds the idle threshold. A third state, called a SUSPEND state, is entered after sensing inactivity for a third period of time greater than the first and second time periods. Another state is OFF which turns off all power for the computer under predetermined conditions.

After having entered one or more of the activity states of the conservation mode, the power management unit switches back to the active mode when activity is sensed by the monitors.

Power Management Unit--FIG. 2

In FIG. 2, a block diagram of the power management unit 15 of FIG. 1 is shown. The power management unit includes a hardware monitor 79 (including an activity monitor 16 and a timer unit 24), a software monitor 80, a state control unit 23, a power control unit 17, a clock control unit 18, and a refresh control unit 20. The hardware monitor 79 (using activity monitor 16) analyzes the address activity on the system bus 5 to provide activity information used to control power management. The timer unit 24 times the activity information sensed by the monitor 16. The state control unit 23 controls the changes among different power consumption states to achieve power management.

The power control unit 17 controls the switches 22-0, . . . , 22-n of FIG. 1 as a function-of the activity sensed by activity monitor 16 and the state determined by state control unit 23.

The clock control unit 18 controls the distribution of and/or the frequency of the CPU and other clocks as a function of the activity sensed by the activity monitor 16 and the state determined by state control unit 23.

The refresh control unit 20 controls the refresh of the RAM memory 11 of FIG. 1 at a rate which is determined by the activity sensed by the activity monitor 16 and state control unit 23.

The power management unit (PMU) 15 is provided to manage power and reduce, over time, the overall power consumption of computer 3. This management is accomplished using an activity monitor 16 to detect periods of system inactivity. During periods of inactivity, power consumption is reduced by reducing clock speeds or removing clocks through clock control unit 18, and/or by removing power through power control unit 17, and/or by controlling the refresh frequency through refresh control unit 20. Standard and slow refresh DRAM support is provided by refresh control unit 20. Inputs are provided to the power management unit 15 which will allow power on or off commands from external sources such as a pushbutton, modem ring indicator, or read-time-clock (RTC) time of day alarm.

Hardware Monitor Generally--FIG. 3

Referring to FIG. 3, the power management unit (PMU) 15 includes the hardware monitor 79 (activity monitor 16 and timer unit 24) which is designed to operate with minimal system requirements and without software support. Power management occurs in response to the hardware monitor independently of any operating system (DOS) or application program support.

In FIG. 3, the PMU 15 has its own power-on reset signal (*RESET) which is produced by a VCC power detector 71, separate from any other reset signal of computer 3, and upon initial power-on, the registers of the power management unit 15 are initialized to preestablished default values to provide basic functionality without need of any software.

While the hardware monitor 79 and the power management unit 15 are provided FIG. 3 as a hardware embodiment, a software embodiment of the hardware monitor 79 is also available.

In accordance with the operation of the hardware monitor 79, a predetermined set of address ranges on bus 5 is monitored by power management unit 15 as part of the power management operation. For example, the predetermined set of address ranges monitored for power management typically includes all of the I/O address range, that is, the addresses of the I/O controllers 6-0 through 6-n and the video memory address range for the video memory locations 8 within the memory 11. Of course, other address ranges can be added to or used as the predetermined set for power management. The set of address ranges including the video memory and the I/O address ranges has been found to provide excellent information for controlling power management.

The hardware monitor 79 senses the activity of addresses on the bus 5. Whenever addresses within the predetermined set of addresses are not present on the bus 5 for predetermined time periods, the power management unit 15 responsively switches power consumption states and controls the consumption of power by different parts of the computer 3.

The power management unit 15 has four main operating states, namely, ON, DOZE, SLEEP, and SUSPEND, and a fifth state which is OFF. The five power management states, under control of the hardware monitor 79, are shown by the state diagram of FIG. 4. The activity monitor 16, external inputs (EXT, RESET), and the timeouts of timer unit 24 generally control the transitions between states in the state control unit 23 as shown in the state diagram of FIG. 4. The CPU 4 of FIG. 1 may also command the PMU 15 to enter any state. The commands from the CPU 4 typically derive from execution of the software monitor 80, but may derive from other CPU 4 commands.

In FIG. 3, each of the four active states (not OFF) has an associated PWR register which indicates in one embodiment which of eight power control outputs VP 0..7! on lines 33 will be active during the state. More generally, any number, (n+1), outputs VP 0 . . . n! can be employed. The PWR registers in power control unit 17 are PWRON register 57, PWRDOZE register 58, PWRSLEEP register 59 and PWRSUSPEND register 60 as shown in FIG. 3. A power control multiplexer 76 selects the eight outputs from one of the registers 57 through 60 corresponding to the current state on STATE lines 34 from unit 23, and these eight outputs drive the VP 0..7! power control outputs from EXOR unit 35. Also, the CPU 4 of FIG. 1 can write, under program control, to any of the PWR registers 57 through 60 to control which of the I/O devices 6 and 7 are powered at any time.

To turn an I/O device on, the corresponding bits in the PWR registers 57 through 60 for the state(s) in which they are to be on is typically high. The POLARITY register 61 specifies the actual polarity of each output VP 0 . . . 7! required to turn the associated one of the switches 22-0, . . . , 22-n on and thereby supply power to the I/O devices 6 and 7. The default value of the POLARITY register is 03h, which implies a logic low to turn on VP 2..7!, which will typically control logic switches 22 with low-true output enables (for example, switches 22 typically include a PNP transistor in the VCC line from power supply 9) and high to turn on the LCD, VP 0!, and EL backlight, VP 1!, power. The value of the VP 0..7! bits just prior to the polarity control by EXOR 35 may be read back through the OUTPUT register 62 to CPU 4 over bus 5.

The system clock oscillator signal CLKI is connected to the CPU Clock Control block 49 to produce the CLKOUT. From there CLKOUT, as controlled by PMU 15 and control block 49, drives CPU 4. The CLKOUT clock can be stopped for static CPU's, or reduced automatically by a divisor specified in the CLOCK field of control register 53 during DOZE and SLEEP states. CLKI is passed through unchanged to CLKOUT in SUSPEND state.

Detailed implementations of the various monitor, control and logic blocks of FIG. 3 will be clear from the following detailed description. Additionally, a software embodiment of the hardware monitor 79 including logic and control functions equivalent to those in the hardware embodiment is available.

Software Monitor Generally

The software monitor 80 of FIG. 2 includes a power management software module linked into the operating system, for example, during boot up time.

The software monitor 80 monitors all the function calls to the operating system. Every time an idle function call is made, the activity measurement, AC(t), is incremented and then checked against thresholds. The incrementing is algebraic by the amount of D_(a), a positive DOS call number, or D_(I), a negative DOS call number.

If the activity measurement, AC(t), is below the idle threshold, T_(H), and the system is in the active mode, no action will be taken. However, if the activity measurement, AC(t), is above the idle threshold, T_(H), the power management software will check the current system status and if in the active mode, will switch to the conservation mode.

The activity measurement, AC(t), is given by the following Eq. (1): ##EQU1## where, D_(a) (t)=Active DOS call numbers as a function of time

D_(i) (t)=Idle DOS call numbers as a function of time

AC(t)=Accumulated Activity Count of DOS call numbers as a function of time, that is, activity measurement

While all of the interrupts of the operating system may be assigned a D_(a) or D_(i) value the following, for example in the following CHART 1.

    ______________________________________                                         CHART 1                                                                        INTERRUPT        CALL NUMBER TYPE                                              ______________________________________                                         I16     (keyboard poll)                                                                             +12         Di                                            I10     (video active)                                                                              -25         Da                                            I8      (timer)      -25         Da                                            I14     (communications)                                                                            -400        Da                                            ______________________________________                                    

Using the values in CHART 1, each time an interrupt 16 (I16) occurs, the software monitor increments AC(t) by +12 and each time I10 or I8 occurs the software monitor increments AC(t) by -25. The value of AC(t) is shown for one example of operation in FIG. 5.

Referring to FIG. 5, the value of AC(t) as a function of t is shown. In the example of FIG. 5, the first eight values of t find keyboard polling occurring by the I16 interrupt so that +12 is added to AC(t) for each of the first eight values of t. In FIG. 5, at t=8, the timer interrupt I8 occurs and subtracts -25 from the AC(t) value. Thereafter the keyboard polling continues until the value of AC(t) reaches 128, the value of T_(H) in the example of FIG. 5. At t=12 in FIG. 5, AC(t) is reset, for example, to 0 when the computer system enters the conservation (idle) mode. At about t=20 in FIG. 5, which may include a long time duration generally indicated by the broken line at about t=15, video interrupt I10 becomes active and starts to add -25 to the AC(t) value until at about time t=35 the value of AC(t) reaches the -256 value of the threshold T_(L).

When the value of AC(t) is above T_(H), then the software monitor is operative to switch the computer system into the conservation mode. Whenever AC(t) is in below the threshold T_(L), the software monitor is operative to switch the computer system back to the active mode.

The example of FIG. 5 is only for purposes-of representing the manner in which AC(t) is incremented as a function of the positive and negative interrupt call numbers. Of course, other counting methods may be employed. After the T_(H) value of +128 is reached, the counter is reset to +256 and each value of Da decrements the count until the threshold TL is reached at 0.

The operation which occurs when the value of AC(t) exceeds the threshold T_(H), is explained with respect to the flowchart of FIG. 6.

In FIG. 6, the value of D (either Da or Di), the interrupt number value, is added as indicated in Eq. (1) to form the accumulation value of the activity measurement, AC(t). This accumulation is indicated by the oval marked D in FIG. 6.

Next, the value of AC(t) is compared with the threshold T_(H). If the value of the summation in Eq. (1) is not greater than the threshold, T_(H), then the N no choice is made the loop repeats so that the next value of D is added to the AC(t) activity measurement. For example, in FIG. 5, this activity continues until approximately t=12 in FIG. 5.

In FIG. 5, at about t=12, the activity measurement AC(t) equals or exceeds the threshold T_(H) and hence the Y output of the comparison connects to the SLEEP state detector. If already in the state, then the Y output will force the computer system to remain in the SLEEP state. If not in the SLEEP state, then the software monitor will force the computer system into the DOZE state.

Note that the FIG. 6 operation will force the computer system into the DOZE or SLEEP state as long as the activity measurement AC(t) exceeds the threshold T_(H). When the threshold T_(H) has been exceeded, AC(t) is reset and remains reset until another activity event, Da or Di, occurs. In FIG. 5, for example, this occurs at about t=20 when AC(t) begins to count toward T_(L).

In addition to the comparison of the activity measurement AC(t) against the upper threshold T_(H), the software monitor 80 also compares the value of the activity measurement against the lower threshold T_(L). This comparison is represented by the flowchart of FIG. 7.

In FIG. 7, the oval represents the incrementing of the activity measurement AC(t) in accordance with Eq. (1). After each incrementing of the activity measurement, the value of AC(t) is compared to determine if it is less than or equal to T_(L). If not, then the N output of the comparison continues the incrementing of the activity measurement for each new value determined in accordance with Eq. (1).

If the activity measurement AC(t) is less than or equal to T_(L), then the Y output of the comparison connects the operation to the activity window comparison.

If AC(t) ≦T_(L) and AW(t) ≦T_(aw), then the FIG. 7 operation switches to the ON state.

If AC(t) ≧T_(H), then test sleep state.

where,

T_(H) ≧K₁

T_(L) ≦K₂

T_(H) =Idle Threshold

T_(L) =Activity Threshold

K₁ =128

K₂ =-256

Combined Hardware Monitor and Software Monitor Operation

If the system is in ON state and AC(t) is greater than or equal to T_(H), the power management software monitor will bring the system into DOZE state. If the system is already in DOZE or SLEEP state, no further action will be needed. Similarly, the activity count, AC(t), will be decremented every time an active function call, Da, is made. The activity count is then used to compare with the active threshold. If the count is higher than the active threshold, T_(H), then the power management software monitor 80 will force the system into the power conservation mode (DOZE or SLEEP) per the FIG. 6 operation regardless of the status of the hardware monitor 79. If the activity count is equal to or less than the active threshold, T_(L), then the system will be programmed into the ON state.

The ON state can also be entered if the hardware monitor 79 detects a predetermined set of address ranges on bus 5. For example, the predetermined set of address ranges monitored for power management typically includes all of the I/O address range, that is, the addresses of the I/O controllers 6-0 through 6-n, and the video memory address range for the video memory locations 8 with the memory 11. Of course, other address ranges can be added to or used as the predetermined set for power management. The set of address ranges including the video memory and the I/O address range has been found to provide excellent information for controlling power management.

After entering the ON state, the power management unit will continue to be in the ON state until any idle function call detects the activity count has reached or gone beyond the idle threshold, T_(H).

There are application programs such as Microsoft's Windows described in connection with FIG. 10 that do not use the DOS idle function calls and therefore the system would never go into the DOZE state through operation of the software monitor 80. Therefore, a watch dog timer is built into the power management software monitor to monitor the absence of idle function calls as indicated in connection with FIG. 7. If a time period greater than T_(aw) as shown in the flow chart in FIG. 7 has been exceeded without any idle function call being made, then it is assumed that the application program bypasses DOS and goes directly to the hardware.

During the T_(aw) time period (see FIG. 7) the power management unit will be forced into the ON state until detection of activity for predetermined period of time, T_(aw). This period, T_(aw) is normally more than a minute in order not to affect the system performance. There is no power saving during the time out period, T_(aw), even if the CPU is actually idling. After the T_(aw) time period, the hardware monitor 79 will take over completely.

In most cases, application programs go through DOS to perform I/O operations. The power management software monitor 80 keeps track of all the operating system function calls. If the accumulative count of all active and idle function calls is greater than the upper threshold, T_(H), then the system is assumed to be inactive. The power management software monitor will program the power management unit to DOZE state only if the system is still in ON state. The computer 3 will enter DOZE state without waiting for the ON state timer to expire and therefore maximizes the power saving of the system. If computer 3 is already in DOZE or SLEEP, no action will be needed from the power management software monitor until the system becomes active again.

In the software monitor 80, inactivity is determined by detecting how many active or idle function calls an application makes within some time period. In the IBM PC DOS environment, the activity status is checked no less frequently than every 50 milliseconds. There are 256 IBM PC DOS function calls and each is labeled as idle or active with a corresponding positive or negative number. A positive number is assigned to an active function call and a negative number to an idle function call. The power management software module keeps a running total of the accumulated value of the function call numbers as the function calls are made. Whenever a function call is made, (either active or idle), the power management software module algebraically adds the number to the accumulated value and decides whether the system is active or not by comparing the magnitude of the accumulated value with a function call threshold. The function call threshold for determining activity is a variable depending on the computer system speed.

To prevent the system from oscillating between the active and idle state due to minor changes in system activity, hysterisis is provided by using active, T_(L), and idle, T_(H), function call thresholds. The accumulated total is clamped at T_(H) after it reaches the active thresholds T_(H) or T_(L) as the case may be. The active and idle thresholds are typically unequal (128 and -256) so that the entry and exit from conservation (idle) mode is biased. For example, in order to have the system enter the idle mode quickly and thereby to reduce power consumption, the active threshold is set with a threshold number (128) greater than the idle threshold number (-256). Also, functions that require immediate attention are assigned numbers large relative to the active and idle thresholds so that a single occurrence of the function call (for example. I14=-400) will force the accumulated count over the active threshold (T_(L) =-256) and thus force the system to be in the active mode. The hysterisis effect can be bypassed by forcing the power management unit into active mode without changing the activity count. In this case, the next idle function call will bring the system back to idle mode.

If the software monitor 80 or the hardware monitor 79 indicates inactivity, the power management unit enters the conservation mode which has multiple states with different levels of power conservation.

The hardware monitor 79 works in conjunction with the software monitor 80 linked to the operating system during boot up time. The state control unit 23 is controlled by the timer unit 24 and power management software module 100. The power management software will override the hardware timer unit 24 whenever inactivity is detected in the operating system level. Since this can be done in a much finer resolution than the hardware monitor 79, the combined software and hardware monitor maximize power saving without any degradation in system performance.

Power Management Unit Detail--FIG. 3 Line List

In FIG. 3, the following lines and functions are defined for the connections output (O) from and input (I) to the PMU 15 of FIGS. 1 and 2.

    ______________________________________                                         Name       Type   Function                                                     ______________________________________                                         SA 0 . . . 9!  I      System Address on bus 5                                  SD 0 . . . 7!  I/O    System Data on bus 5                                     VP0            O      LCD power control                                        VP1            O      EL backlight power control                               VP 2 . . . 7!  O      Peripheral power control                                 *RAS           O      *RAS for DRAM                                            *CAS           O      *CAS for DRAM                                            *PCRAS   I     *RAS for DRAW                                                   *PCCAS   I     *CAS for DRAM                                                   *VCS           I      Video RAM chip select                                    *IOR           I      I/O Read                                                 *IOW           I      I/O Write                                                *S1            I      Status, low indicates read or mem                                              read  operation                                          AEN            I      DMA enable                                               INMI           I      NMI input from user system                               NMI            O      NMI output to CPU                                        INTR           I      Int request output of computer                           DRQ 0 . . . 3! I      DMA requests which could occur in                                              DOZE   or SLEEP                                          *DACKO   I     Indicates refresh DMA cycle                                     EXT            I      External command input (button)                          RI       I     Ring indicator from modem                                       RTC            I      Alarm output from RTC                                    CLKI           I      CPU clock input                                          CLKOUT   O     Clock out to CPU                                                LB       I     Low battery detect, first warning                               LLB            I      Low battery detect, second warning                       ACPWR    I     AC power good input                                             *RESET   I     External RC required for reset                                  *REFRSEL       O      Low when PMU controls DRAM refresh                       OSC            I      Xtal osc output                                          CLK1IN   I     Clock 1 in for switched clock 1 out                             CLK1OUT  O     Switched clock 1 out                                            CLK2IN   I     Clock 2 in for switched clock 2 out                             CLK2OUT  O     Switched clock 2 out                                            LBPOL    I     Low battery polarity select                                     STATIC.sub.-- CPU                                                                        I Connect to Vcc if CPU is static                                    VCC           Power                                                            VSS           Ground                                                           ______________________________________                                    

Registers

In FIG. 3, the PMU 15 includes a number of registers accessed for read or write by CPU 4 over bus 5 via an index register addressing scheme. When not accessed by CPU 4, for example, after a power on detection by detector 71, the registers are all initialized to a default state. When accessed by CPU 4, an index value is first written to the index register 50 from bus 5 and the index value is decoded by decoder 70 to select one of the registers of PMU 15 for access to bus 5 to receive or send information from or to CPU 4. The index register 50, after an index write, is changed to point to another register to be accessed. When reset, the index register is not active to enable any PMU 15 register. This is a safety feature to help prevent applications executing on the CPU 4 from inadvertently accessing PMU 15 registers. All registers may be read and written over bus 5.

The PMU 15 data registers are:

    ______________________________________                                         Data Register (Ref. No.-FIG. 3)                                                                     Index Decode                                              ______________________________________                                         STATUS           51      00H                                                   SUPPLY           52      02H                                                   CONTROL          53      04H                                                   ACTMASK          54      06H                                                   NMIMASK          55      08H                                                   OSC              56      0AH                                                   PWRON            57      OCH                                                   PWRDOZE          58      0EH                                                   PWRSLEEP         59      10H                                                   PWRSUSPEND       60      12H                                                   POLARITY         61      14H                                                   OUTPUT           62      16H                                                   DOZE             63      18H                                                   SLEEP            64      1AH                                                   SUSPEND          65      1CH                                                   LCD              66      1EH                                                   EL               67      20H                                                   ______________________________________                                         Status Register                                                                Bit       Name        Function                                                 ______________________________________                                         D7        RESUME      Resuming from SUSPEND                                                          (warm start)                                             D6        WU1         Wakeup code MSB                                          D5        WU0         Wakeup code LSB                                          D4        NMI2        \                                              D3        NMI1        >NMI cause code                                          D2        NMI0        /                                                        D1        STATE1      State MSB                                                D0        STATE0      State LSB                                                ______________________________________                                    

In register 51, only D0 and D1 are affected by a write. The CPU 4 can write the state code to this register to put the PMU in another state. Writing OFFh puts it in the OFF state. The NMI cause, state and wakeup codes are decoded as follows:

    ______________________________________                                         Code                                                                           Wakeup NMI Cause    Code    State   Code Cause                                 ______________________________________                                         000    None, or INMI                                                                               00      On      00                                         001    EXT input    01      DOZE    01   E X T                                 input                                                                          010    LB           10      SLEEP   10   R T C                                 input                                                                          011    LLB timeout  11      SUSPEND 11   R I                                   input                                                                          100    SLEEP timeout                                                           101    SUSPEND timeout                                                         ______________________________________                                          *RESET sets STATE 0 . . . 1! and clears all other bits.                  

Supply Register

This register 52 is read only. D 0..2, 5! are driven directly by the input lines. Bit D3 is set when system activity is detected and is cleared when this register is read.

    ______________________________________                                         Bit   Name        Function                                                     ______________________________________                                         D5    STATIC.sub.-- CPU                                                                          1 = Static CPU (clock stops in                                                    DOZE)                                                     D4    DRAMRDY     1 = CPU controls DRAM (same as                                                    *REFRSEL)                                                 D3    ACTIVITY    System activity present                                      D2    LLB         Low battery 2 (second warning)                               D1    LB          Low battery 1 (first warning)                                D0    ACPWR       AC power input in range                                      ______________________________________                                         Control Register                                                               Bit  Name       Default Function                                               ______________________________________                                         D7              0                                                              D6   RING2      0       \                                            D5   RING1      0       > Number of RI pulses required                                                 for turnon                                             D4   RING0      1       / default = 1                                          D3   STATIC.sub.-- CPU                                                                         0       For static CPU's                                       D2   SLOW       0       Clock runs slow in ON                                  D1   CCLK1      1       CPU Clock divisor, DOZE and SLEEP                      D0   CCLK0      0       / default divisor = 4                                  ______________________________________                                    

In register 53, the RING 0..2! bits are used to set the number of RI pulses required for turnon. The default value is 1 so that only one pulse is required for turnon. If set to 0, RI is disabled. State logic 23 has conventional logic for detecting and counting RI pulses from a modem, one of the I/O peripherals 7-0 to 7-n. D3 is only used for static CPU's. SLOW indicates reduced clock speed operation in On. The CCLK 0..1! bits select the clock divisor for CLKOUT in SLEEP and DOZE states, and in ON if SLOW is set, according to the table.

    ______________________________________                                                CCLK 0 . . . 1!                                                                               Divisor                                                  ______________________________________                                                0              1                                                               1              2                                                               2              4                                                               3              8                                                        ______________________________________                                         ACTMASK Register                                                               Bit   Name       Default  Function                                             ______________________________________                                         D7               0                                                             D6    MSK.sub.-- VIDM                                                                           0        Mask access to video memory                          D5    MSK.sub.-- DMA                                                                            0        Mask all DMA activity                                D4    MSK.sub.-- P63                                                                            1        Mask access to port 63h                              D3    MSK.sub.-- PIC2                                                                           0        Mask access to port A0h, A1h                         D2    MSK.sub.-- RTC                                                                            1        Mask access to port 70h, 71h                         D1    MSK.sub.-- KBD                                                                            0        Mask keyboard (port 60H, 64H)                        D0    MSK.sub.-- IO                                                                             0        Mask access to all ports not                                                   maskable by D 2 . . . 5!                             ______________________________________                                    

The activity monitor ACTIVITY output is the logical OR of all unmasked activity sources. This register 54 affects only the ACTIVITY output. Refresh DMA cycles (*DACKO low), interrupts, or accesses to the PMU 15, never affect the activity monitor 16.

NMIMASK Register

This register 55 masks the various NMI sources. In the default state only the INMI input can generate NMI.

    ______________________________________                                         Bit                                                                            Default  Name         Function                                                 ______________________________________                                         D6       OS2          Mask INMI input 0                                        D5       MSK.sub.-- SUSPEND                                                                          Mask SUSPEND timeout                                                                           1                                        D4       MSK.sub.-- SLEEP                                                                            Mask SLEEP timeout                                                                             1                                        D3       MSK.sub.-- LLB                                                                              Mask LLB input  1                                        D2       MSK.sub.-- LB                                                                               Mask LB input   1                                        D1       MSK.sub.-- EXT                                                                              Mask EXT input  1                                        ______________________________________                                         OSC Register                                                                   Bit     Name        Default  Function                                          ______________________________________                                         D7      OSCDIV3     1        \                                       D6      OSCDIV2     1        OSC input divisor -1                              D5      OSCDIV1     0        default code = 1101                                                            (divisor = 14)                                    D4      OSCDIV0     1        /                                                 D3                                                                             D2      SLWREF      0        Slow refresh DRAM                                 D1      RASWIDTH1   0        *RAS pulse width MSB                              D0      RASWIDTH0   0        *RAS pulse width LSB                              ______________________________________                                    

Referring to register 56, OSCDIV 0..3! plus one is the OSC frequency in MHz, except for OSCDIV 0..3!=13, the default, indicates 14.318 MHz. SLWREF is set when slow refresh DRAM is used. RASWIDTH 0..1! indicates the width of the *RAS pulse in units of OSC periods. The default value is 0 which disables refresh in SUSPEND state, and no RAS/CAS is generated. Values of 1 to 3 indicate 1 to 3 OSC periods.

PWR Registers

The bits D 0..7! in these registers 57 through 60 correspond directly with the power control outputs VP 0..7!. In a particular state, the corresponding PWR register outputs control the VP lines 23. The exception is VP0 and VP1 which are LCD and EL power, respectively. These outputs are AND'ed in AND gates 41 and 42 with the LCD and EL timer outputs prior to driving the lines 33. All bits are then exclusive NOR'ed in gates 35 with the POLARITY register 61, and the result drives the lines 33. The default values for these registers are as follows, where 1 indicates that the controlled device is on:

    ______________________________________                                                PWRON           FFh                                                            PWRDOZE         FFh                                                            PWRSLEEP        0Fh                                                            PWRSUSPEND      00h                                                     ______________________________________                                    

Polarity Register

This register 61 controls the polarity of the VP outputs. If a logic low is required on a VP line to turn the external device on, the corresponding bit in the POLARITY register 61 must be low. If a high is required, set the bit high. The default value is 03h.

Timer Registers

The nonzero value loaded into one of the timer registers 63 through 68 is the actual timeout minus one. A zero disables the timeout. Therefore a 4 bit timer can be set for a timeout from 1 to 15 time units. Reading a timer register returns the value that was last written to it, not the actual time remaining. The default values are tabulated below:

    ______________________________________                                         Timer          Range       Default                                             ______________________________________                                         DOZE           1-15 sec    5 sec                                               SLEEP          1-15 min    2 min                                               SUSPEND        5-75 min    0 (disabled)                                        LCD            1-15 min    TBD                                                 EL             1-15 min    TBD                                                 ______________________________________                                    

OUTPUT Register

The OUTPUT register 62 is a read only register. For each VP 0..7! output that is on, the corresponding bit in the OUTPUT register will be set.

The control and logic functions for the activity monitor 16, the state logic 23, the NMI logic 21, and other components of FIG. 3 are conventional logic circuits for implementing the logic and control functions hereinafter described or alternatively are software logic.

ON State

Referring to FIG. 4, the ON state is entered from the SUSPEND or OFF state when the *RESET input is low, and also when one of EXT, RTC or RI goes high if ACPWR is true or LB is false. It is entered from DOZE or SLEEP when the activity monitor 16 detects activity with addresses in the predetermined address set. In the ON state encoded on lines 34, all power control outputs VP 0 . . . n! will be controlled by the PWRON register 57. Upon entering the ON state, the DOZE timeout timer 63 will be retriggered. The LCD and EL timeouts in timers 66 and 67 will be retriggered when entering the ON state from SUSPEND or OFF. The retrigger lines from STATE logic 23 to the timers are not shown in FIG. 3 for clarity.

In FIG. 3, the STATE logic 23 receives the CPU data bus D(0 . . . 7) from bus 5 for receiving state commands issued by the software monitor 80 of TABLE 2. The STATE logic also receives the address detection line 76 from activity monitor 16 which enables the STATE logic 23 to receive the state commands from the software monitor when addressed over the bus 5.

If the SLOW bit in the control register 53 is false, the CLKOUT rate on line 28 will be full speed. If the SLOW bit is true, CLKOUT will be as specified by the CCLK 0,1! bits in register 53. This clock control allows the user to save power, for example, when running non-computationally intensive applications such as a database application (see FIG. 8) or word processing (see FIG. 9).

DOZE State

The DOZE state is entered from the ON state when the activity monitor 16 has not detected activity and therefore has not provided the ACTIVITY signal within the time, T1, specified by the DOZE timer 63. In the DOZE state encoded on lines 34, the power control outputs VP 0 . . . 7! from unit 17 are controlled by the PWRDOZE register 58. If a non-static CPU 4 is used, the clock on line 28 will be slowed as specified by CCLK 0,1! in register 53.

If a static CPU 4 is used, CLKOUT on line 28 will stop in the low state immediately following a non-DMA memory read instruction, as indicated by *S1 going high while *AEN is low, so that no chip select will be low. If INTR goes high, CLKOUT will be enabled until after EOI is written to the interrupt controller with INTR false. If INMI goes high, CLKOUT will be enabled. If an internally generated NMI occurs, CLKOUT will be enabled until the NMIMASK register 55 is read. If any DRQ goes high, CLKOUT will be enabled until after the next memory read instruction with AEN and all DRQ inputs false. The enable request functions for INTR, INMI, internal NMI and DMA are separate and CLKOUT is enabled when any event requests it, so that an interrupt handler in CPU 4 will run to completion even if it is interrupted by a DMA request. These enable request functions are independent of the activity monitor and the ACTMASK register 54. Enabling CLKOUT does not cause the PMU 15 to leave DOZE, unless the activity monitor 16 is subsequently triggered. If this trigger occurs, the PMU 15 will enter the ON state and the enable request logic will be cleared.

SLEEP State

The SLEEP state is entered when the PMU 15 has been in the DOZE state for the time, T2, specified by the SLEEP timer 64 and no ACTIVITY signal has occurred. In the SLEEP state, the CLKOUT operation is the same as in DOZE. The power control outputs are controlled by the PWRSLEEP register 59.

Alternatively, the PMU can be programmed to generate NMI and remain in DOZE state instead of automatically entering SLEEP.

SUSPEND State

The SUSPEND state is entered when the PMU 15 has been in the SLEEP state for the time, T3, specified by the SUSPEND timer 65 or when a power check detects low battery signals, LB or LLB. The SUSPEND state is entered after these conditions only when the CPU 4 writes the code for SUSPEND to the STATUS register 40 and this operation requires software support because in SUSPEND the CPU operation is affected. In SUSPEND operation, CLKOUT is the same as CLKI. The power control outputs are controlled by the PWRSUSPEND register 60. In SUSPEND, the CPU 4 and the device (for example, a switch) which generates the system reset signal must be powered off. Only activity on the EXT, RI or RTC inputs can cause an exit from SUSPEND, and the new state after exit will be ON. When the reset circuit power is restored, it will reset the CPU 4, which will then execute a warm startup routine in a conventional manner. DRAM refresh may be enabled in SUSPEND. If DRAM refresh is not enabled, the PMU 15 does not need OSC from unit 43 in SUSPEND, and gates it off internally to minimize OSC power consumption. The OSC output will stay low. The bus interface is inhibited, and the data bus 5 is tristated.

OFF State

The OFF state is entered when the CPU 4 writes the code of OFF (OFFh) to the STATUS register 51. It is also entered 5 seconds after the EXT input goes high if the NMI is not serviced.

The OFF state is meaningful only when the PMU 15 is powered from a battery while the rest of the computer 3 is turned off. This type of power connection is necessary only if the PMU 15 must awaken the system from the OFF state by activating VP outputs on lines 33 in response to transitions on the EXT input. If this function is not required, then the PMU 15 may be powered off when the system is powered off, and the OFF state as described below is not required.

In the OFF state, all outputs from the PMU 15 are either low or tristated, and all devices other than PMU 15 in the computer 3 are powered off. Any inputs will have pulldowns so that floating inputs, if any, will not cause increased power dissipation. Only activity on the EXT, RI or RTC inputs can cause an exit from OFF, and the new state will be ON. The bus interface is inhibited and data bus 5 is tristated.

Activity Monitor

The activity monitor 16 includes an address detector 73 which receives addresses from bus 5 representing the address activity of the CPU 4. The address detector 73 receives, for example, control lines and address lines SA(0 . . . 9) from bus 5 for sensing when those addresses are within the predetermined address set. The predetermined address set is defined, for example, by an address set specified by ACTMASK register 54. The detector 73 compares or masks the address set specified by register 74 with the addresses on bus 5 and provides an address detect signal on line 76 to the logic 77. The logic 77 receives the other inputs to the activity monitor 16 and combines them, using conventional logic circuitry, to provide three outputs.

The three outputs provided by activity monitor 16 are produced by conventional logic or by software. The EXTRIG output is a function of keyboard activity only and is used to retrigger the EL backlight timer 67. The LCDTRIG output is true for keyboard activity or video memory writes, and retriggers the LCD timer 66. The ACTIVITY output is an OR function of a programmable selection of different activities specified in the ACTMASK register 54. When active, this output returns the PMU 15 to the ON state and retriggers the DOZE timeout timer 63. The activity monitor 16 does not produce the ACTIVITY output in response to accesses to the registers of PMU 15.

OSC Programmability

The OSC frequency of refresh control unit 20 provides the timebase for the timers and the refresh for DRAM memory 11. The PMU 15 may be programmed to accept a range of OSC frequencies. The OSC frequency of oscillator 43 is fed to a counter 44 which divides it by a divisor which is programmed in the OSC register 56. The programmable counter output of divider 44 is divided to produce 256 Hz which is used by the refresh control logic 48. Further dividing in divider 46 produces 32 Hz for slow refresh to refresh control logic 48, and 8 Hz and 1/(7.5) Hz for use by the timers 63, 64, 65 and 68.

Timers

There are six timers in the PMU 15, namely, DOZE timer 63, SLEEP timer 64, LB (low battery) timer 68, SUSPEND timer 65, EL (backlight) timer 66, and LCD timer 67. Each of the six timers a 4-bit register loadable by CPU 4 over bus 5. Setting a timer register to 0 disables it; setting it to a nonzero value enables it. If enabled, certain timers are triggered by the transition to the ON state. Individual timers are also triggered by events specific to their functions. Some timers are retriggerable, timing out at a programmable time following the last trigger.

The DOZE timer 63 is programmable from 1 to 15 seconds with a resolution of 1 second, and the SUSPEND timer 65 is programmable from 5 to 75 minutes with a resolution of 5 minutes. All other timers are programmable from 1 to 15 minutes with a resolution of one minute. There is a quantization error associated with retriggering any timer. This error is a quantization error associated with retriggering any timer. This error will cause the actual timeout to be up to 1/8 of the resolution of the timer longer (but never shorter) than the programmed value. The error does not vary with the programmed value.

The LCD timer 66 and the EL timer 67 are retriggerable. The timer outputs are AND'ed in AND gates 41 and 42 with the power control bits selected by the power control multiplexer 76 according to the current PMU state to control the LCD (VP0) and EL (VP1) power control outputs to EXOR 35. This operation provides the flexibility to turn the EL and LCD outputs off when the associated timers 66 and 67 time out, or to control the outputs in any PMU power-management state under control of multiplexer 76.

The DOZE timer 63 is retriggerable and is triggered by the activity monitor ACTIVITY output in the ON state, and triggers the transition to DOZE state when it times out.

The SLEEP timer 64 is triggered when the DOZE state is entered and is cleared when the DOZE state is exited. Timer 64 either generates NMI or triggers the transition to SLEEP state when it times out.

The SUSPEND timer 65 is triggered when the SLEEP state is entered and is cleared when SLEEP is exited. If unmasked, an NMI will be generated when it times out.

The LB timer 68 is enabled when ACPWR is false (no AC power). Timer 68 is triggered when LB is first detected. If unmasked, NMI is generated by the LB timer 68 output once per minute when it times out, until a period of one minute elapses during which LB remains continuously false. The NMI cause will be identified as an LB or LLB interrupt. Software can maintain a counter and display a message once per X interrupts. It can also monitor LLB and shut the computer down after Y interrupts. It can also monitor LLB and shut the computer down after Y interrupts with LLB true.

NMI

The PMU unit 15 OR's together a number of internally generated NMI requests to produce the NMI output on line 27. These requests can be masked by bits in the NMIMASK register 55. The INMI input comes from conventional external NMI-generating logic such as a parity detector, and can be OR'ed with the internal NMI requests to generate NMI when unmasked by the OS2 bit in the NMIMASK register 55. The NMI output on line 27 generally goes to the CPU NMI input, except on OS2 systems where it must go to an IRQ. The NMI CAUSE code bits in the Status register 40 indicate the cause of the NMI on line 27. An internally generated NMI is cleared by reading the NMIMASK register 55.

NMI may be generated to indicate a low battery when ACPWR is false.

If the MSKSLEEP bit is cleared, the PMU 15 will generate NMI when the SLEEP timer 64 times out and remain in DOZE instead of entering SLEEP.

NMI is also generated when the SUSPEND timer 65 times out. Software can then save status and go to SUSPEND or OFF state.

A high on the EXT input while not in the OFF or SUSPEND state will generate NMI. Software can then save status and go to SUSPEND or OFF state. If the NMI is not serviced within 5 seconds, the PMU assumes there is no software support for SUSPEND and will turn all power off and enter the OFF state.

Refresh In SUSPEND State

Refresh is enabled by setting the RASWIDTH 0..1! bits in the OSC register 56 to a nonzero value. This enables OSC to run in SUSPEND mode, and the RASWIDTH value also sets the width of the *RAS pulse in units of OSC clock periods. Slow refresh is enabled by setting SLWREF high. The PMU 15 generates *MRAS and *MCAS signals to mux 32 to refresh DRAM while the CPU is powered off or being reset. When the CPU is active, the *PCRAS, *PCCAS signals on lines 30 from the PC controller 13 are selected by multiplexer 30 to provide the *RAS, *CAS signals on lines 29. *REFRSEL on line 72 will go low to indicate that the PMU 15 is controlling refresh and high for PC controller 13 control.

If enabled, the DRAM refresh outputs are active in SUSPEND. When entering SUSPEND, the PMU 15 immediately generates a burst of 1024 CAS before RAS refresh cycles. A burst of 256 cycles is then repeated every 3.9 ms if SLOWREF is false or every 31.25 ms if SLOWREF is true. After entering the ON state from SUSPEND, the PMU 15 generates bursts of 1024 refresh cycles over 2.9 ms. This operation allows as much time as needed for CPU power stabilization, crystal oscillator startup and CPU reset. When the CPU is ready to take over control of the DRAM, it must poll the SUPPLY register 38 until the DRAMRDY bit goes high. The PMU 15 senses the polling operation as a request from the CPU for DRAM control, and at the end of the first refresh burst following a CPU I/O read of the SUPPLY register 38, the PMU 15 sets *REFRSEL high to return control of the DRAM to the CPU. The DRAMRDY bit is essentially the same signal as *REFRSEL.

The purpose of the bursts when entering and leaving SUSPEND is to eliminate violations of the refresh rate spec when switching between external refresh row address generation (DMA cycles during ON) and internal row address generation (CAS before RAS during SUSPEND).

Pseudostatic RAM refresh is also supported. When *REFRSEL goes low, *RAS can drive *RFSH low for auto refresh mode. The burst refresh will assure that switching between external and internal refresh will not violate the refresh rate spec. Self refresh can also be used by driving *RFSH low when *REFRSEL is low, but other logic will have to generate the refresh burst when entering and leaving SUSPEND, if required.

External Wakeup Inputs

RI is a rising edge sensitive input, to state logic 23 from a modem ring indicator RI output of a peripheral 7. The number of rising edges required for this input to be recognized is specified in bits D 4..6! of the Control register 53. The default is one transition. If these bits are zero, this input is disabled. If enabled, a rising transition on this input will force the PMU 15 to the ON state.

RTC is an edge sensitive wakeup-alarm input from a real time clock in CPU clock control 49 of FIG. 3. A rising or falling transition on this input will force the PMU 15 to the ON state.

EXT is a rising edge sensitive input, intended for use with an external pushbutton. A rising transition on this input while the PMU 15 is in OFF or SUSPEND will force the PMU 15 to the ON state. A transition in ON, DOZE or SLEEP will generate NMI.

EXT is debounced in ON, DOZE and SLEEP in a conventional debouncer circuit 36. A rising edge immediately generates NMI but only if EXT has been sampled low at least twice by a 32 Hz debounce clock from counter 46 prior to the rising edge. The debounce clock is derived from OSC 43 and therefore may be stopped in SUSPEND and OFF, so the PMU 15 will not enter these states until the debounce operation is completed. To prevent resuming due to contact bounce on the release of a pushbutton, the PMU 15 will defer execution of a change of state command from the CPU 4 until after the EXT input has been sampled low twice by the debounce circuit 36. This operation is typically transparent to software. For example, if the user presses the button in ON, the PMU 15 will generate NMI, and the CPU will write the command to enter SUSPEND and then execute a halt instruction. Nothing will happen until after the pushbutton is released, at which time the PMU 15 will enter SUSPEND.

Resume and Power On

The PMU 15 has its own private *RESET signal, typically from an external RC network detector 71 which detects VCC. This signal resets only the PMU 15 when power, VCC, is first applied to it. A separate reset signal must be generated by external hardware for the CPU when entering the ON state from SUSPEND or OFF state. At power on, the CPU 4 must read the RESUME bit in the Status register 51. RESUME will be cleared if the startup is a cold start from OFF and will be set to indicate a warm start (resume) from SUSPEND. If RESUME is cleared, the wakeup bits WU 0..1! in the Status register 51 will be zero, otherwise they will indicate which external input caused the resume. The RESUME bit will be cleared after the Status register is read.

Clock Switching

The clock switch control 69 is provided to switch input clocks CLK1IN and CLK2IN clocks to output clocks CLK1OUT AND CLK2OUT for peripherals. The CLK1 and CLK2 operations are the same. For example, the CLK1IN is passed to the CLK1OUT output by control 69 in ON and DOZE. When entering SLEEP mode, CLK1OUT will stop synchronously in the low state. CLK1OUT will start synchronously when returning to the ON state.

Low Battery Detection

The LB and LLB inputs indicate low battery and low low battery as generated by a conventional battery level detector in power supply 9 of FIG. 1. The polarity of these inputs is programmable by the LBPOL line which can be strapped low or high. If this line is high, LB and LLB are high true. If low, these inputs are low true. The status of the LB and LLB lines after polarity correction can be read in the SUPPLY register 38. A low battery indication can generate NMI.

Power Sequencing

To minimize turnon transients, the turnon of VP1 (EL power) is delayed by 4 to 8 ms after OSC begins clocking, when entering the ON state.

                  TABLE 1                                                          ______________________________________                                         ;==================================================                            ;   Power Management Software                                                  ;==================================================                            ;     Copyright -- 1989 Vadem, Inc.                                            ;                                                                              ;     All Rights Reserved.                                                     ;                                                                              ;         C:                                                                   ;==================================================                            .xlist                                                                         include                                                                              romeq.dec                                                                include                                                                              romdef.dec                                                               include                                                                              seteq.dec                                                                include                                                                              clkeq.dec                                                                include                                                                              8250eq.dec                                                               include                                                                              prneq.dec                                                                include                                                                              crteq.dec                                                                include                                                                              vg600.dec                                                                include                                                                              notes.dec                                                                include                                                                              kbdeq.dec                                                                .list                                                                          include                                                                              pwreq.dec                                                                CMSG  <Power Management BIOS Kernel>                                           pmdata                                                                               segment  para public  `pmdata`                                           extrn on.sub.-- power.sub.-- status:word                                       extrn sleep.sub.-- power.sub.-- status:word                                    extrn lb.sub.-- event.sub.-- handler:dword                                     extrn lb.sub.-- event.sub.-- mask:word                                         extrn doze.sub.-- timeout:byte                                                 extrn doze.sub.-- count:byte                                                   extrn sleep.sub.-- timeout:byte                                                extrn sleep.sub.-- count:byte                                                  extrn kbd.sub.-- timeout:byte                                                  extrn kbd.sub.-- count:byte                                                    extrn pwr.sub.-- off.sub.-- timeout:word                                       extrn pwr.sub.-- off.sub.-- count:word                                         extrn led.sub.-- time.sub.-- on:byte                                           extrn led.sub.-- time.sub.-- off:byte                                          extrn led.sub.-- next.sub.-- event:byte                                        extrn led.sub.-- cycle.sub.-- count:word                                       extrn lb.sub.-- def.sub.-- event.sub.-- type:byte                              extrn lb.sub.-- event.sub.-- rep:byte                                          extrn lb.sub.-- event.sub.-- count:byte                                        extrn sleep.sub.-- save.sub.-- buf:byte                                        extrn pm.sub.-- flags:byte                                                     extrn second.sub.-- counter:byte                                               extrn minute.sub.-- counter:byte                                               extrn one.sub.-- shot.sub.-- handler:dword                                     extrn one.sub.-- shot.sub.-- timer:dword                                       extrn lb.sub.-- last.sub.-- event:word                                         extrn pm.sub.-- ram.sub.-- chksum:word                                         extrn pm.sub.-- save.sub.-- ss:word                                            extrn pm.sub.-- save.sub.-- sp:word                                            extrn pm.sub.-- resume.sub.-- stack:byte                                       pmdata                                                                               ends                                                                     data0 segment public `DATA0`                                                   extrn crt.sub.-- addr:word                                                     extrn reset.sub.-- flag:word                                                   data0 ends                                                                     code  segment  word public  `code`                                             assume                                                                               cs:code, ds:pmdata                                                       public                                                                               power.sub.-- management                                                  ,power.sub.-- management.sub.-- init,power.sub.-- management.sub.--            enable                                                                         public                                                                               pm.sub.-- timer.sub.-- hook,pm.sub.-- kbd.sub.-- hook                    public                                                                               pm.sub.-- enter.sub.-- sleep, read.sub.-- com, write.sub.-- com          public                                                                               write.sub.-- crt.sub.-- reg, read.sub.-- crt.sub.-- reg                  public                                                                               suspend, resume                                                          extrn data0p:word                                                              extrn get.sub.-- pm.sub.-- ds:near                                             extrn alloc.sub.-- pm.sub.-- ds:near                                           extrn default.sub.-- low.sub.-- battery.sub.-- alarm:near                      extrn rd.sub.-- rtcw:near                                                      extrn wr.sub.-- rtcw:near                                                      extrn rd.sub.-- rtcb:near                                                      extrn wr.sub.-- rtcb:near                                                      extrn play.sub.-- song:near                                                    extrn set.sub.-- ibm.sub.-- timer:near                                         extrn checksum:near                                                            extrn oem.sub.-- pm.sub.-- init:near                                           extrn oem.sub.-- pm.sub.-- get.sub.-- status:near                              extrn oem.sub.-- pm.sub.-- extensions:near                                     extrn oem.sub.-- pm.sub.-- halt:near                                           extrn oem.sub.-- pm.sub.-- activity?:near                                      extrn oem.sub.-- pm.sub.-- reset.sub.-- activity:near                          extrn oem.sub.-- pm.sub.-- toggle.sub.-- led:near                              extrn oem.sub.-- pm.sub.-- turn.sub.-- on.sub.-- peripherals:near              extrn oem.sub.-- pm.sub.-- turn.sub.-- off.sub.-- peripherals:near             extrn oem.sub.-- pm.sub.-- power.sub.-- off:near                               extrn oem.sub.-- pm.sub.-- suspend:near                                        extrn oem.sub.-- pm.sub.-- blank.sub.-- video:near                             extrn oem.sub.-- pm.sub.-- restore.sub.-- video:near                           extrn oem.sub.-- pm.sub.-- save.sub.-- peripherals:near                        extrn oem.sub.-- pm.sub.-- restore.sub.-- peripherals:near                     extrn oem.sub.-- pm.sub.-- save.sub.-- video.sub.-- state:near                 extrn oem.sub.-- pm.sub.-- restore.sub.-- video.sub.-- state:near              extrn oem.sub.-- pm.sub.-- kbd.sub.-- activity?:near                           extrn oem.sub.-- pm.sub.-- reset.sub.-- kbd.sub.-- activity:near               extrn oem.sub.-- pm.sub.-- make.sub.-- power.sub.-- off.sub.-- noise:near            8                                                                        extrn oem.sub.-- pm.sub.-- make.sub.-- low.sub.-- battery.sub.-- noise:nea           r                                                                        extrn oem.sub.-- pm.sub.-- defaults:near                                       extrn oem.sub.-- pm.sub.-- get.sub.-- hw:near                                  extrn oem.sub.-- pm.sub.-- get.sub.-- nmi.sub.-- handler:near                  es.sub.-- arg                                                                        equ    word ptr  bp+16!                                                  ah.sub.-- arg                                                                        equ    byte ptr  bp+15!                                                  al.sub.-- arg                                                                        equ    byte ptr  bp+14!                                                  ax.sub.-- arg                                                                        equ    word ptr  bp+14!                                                  cx.sub.-- arg                                                                        equ    word ptr  bp+12!                                                  cl.sub.-- arg                                                                        equ    byte ptr  bp+12!                                                  ch.sub.-- arg                                                                        equ    byte ptr  bp+13!                                                  dx.sub.-- arg                                                                        equ    word ptr  bp+10!                                                  dl.sub.-- arg                                                                        equ    byte ptr  bp+10!                                                  dh.sub.-- arg                                                                        equ    byte ptr  bp+11!                                                  bh.sub.-- arg                                                                        equ    byte ptr  bp+09!                                                  bl.sub.-- arg                                                                        equ    byte ptr  bp+08!                                                  bx.sub.-- arg                                                                        equ    word ptr  bp+08!                                                  bp.sub.-- arg                                                                        equ    word ptr  bp+04!                                                  si.sub.-- arg                                                                        equ    word ptr  bp+02!                                                  di.sub.-- arg                                                                        equ    word ptr  bp+00!                                                  page                                                                           pwrmgt.sub.-- fx.sub.-- table  label word                                      dw    pm.sub.-- get.sub.-- profile                                                                      ;get current profile                                  dw    pm.sub.-- get.sub.-- rtc.sub.-- profile                                                           ;get profile in rtc                                   dw    pm.sub.-- set.sub.-- profile                                                                      ;set active profile                                   dw    pm.sub.-- set.sub.-- rtc.sub.-- profile                                                           ;update rtc profile                                   dw    pm.sub.-- event.sub.-- handler                                                                    ;install evt handler                                  dw    pm.sub.-- one.sub.-- shot.sub.-- event.sub.-- handler                                             ;install evt handler                                  dw    pm.sub.-- get.sub.-- pm.sub.-- status                                                             ;get status                                           dw    pm.sub.-- enter.sub.-- sleep                                                                      ;enter sleep                                          dw    oem.sub.-- pm.sub.-- power.sub.-- off                                                             ;power off                                            dw    oem.sub.-- pm.sub.-- suspend                                                                      ;suspend                                              pwrmgt.sub.-- fx.sub.-- table.sub.-- len  equ ($-pwrmgt.sub.-- fx.sub.--       table)/2                                                                       ;==================================================                            ;   power.sub.-- management.sub.-- init                                        ;==================================================                            ;                                                                              ;   Called to initialize the Data Structures for                               ;   the power management kernel. Allocate a Data Segment                       ;   initialize variables, install the default                                  ;   Low Battery event handler, and call oem.sub.-- pm.sub.-- defaults          ;   to setup any system specific hardware or default                           ;   settings. Does not enable the power management yet . . .                   power.sub.-- management.sub.-- init proc                                       dbMESSAGE fTEST8+fTESTb <power.sub.-- management.sub.-- init>                  call   alloc.sub.-- pm.sub.-- ds                                                                        ;now sets ds . . .                                    sub    ax, ax                                                                  mov    pm.sub.-- flags, al                                                     mov    second.sub.-- counter, 18                                               mov    minute.sub.-- counter, 60                                                                        ;init this stuff . . .                                mov    ax,(SYS.sub.-- PWR.sub.-- MGT shl 8) or GET.sub.-- RTC.sub.--                  PWR.sub.--                                                              PROFILE                                                                        int    TASKINT                                                                 push   dx                ;save power off timeout                               mov    ax,(SYS.sub.-- PWR.sub.-- MGT shl 8) or SET.sub.-- PWR.sub.--                  PROFILE                                                                 int    TASKINT                                                                 mov    ah, CM.sub.-- ALM.sub.-- REP                                                                     ;get alarm repeat                                     call   rd.sub.-- rtcb                                                          mov    cl, al            ;input param                                          mov    ah, CM.sub.-- DEF.sub.-- ALM                                            call   rd.sub.-- rtcb                                                          mov    bl, al                                                                  and    bx, LBE.sub.-- LB1 or LBE.sub.-- LB2                                                             ;default event type . . .                             pop    dx                ;restore pwr.sub.-- off.sub.-- timeout                mov    ax,(SYS.sub.-- PWR.sub.-- MGT shl 8) or INSTALL.sub.-- LP.sub.--               EVT.sub.--                                                              HANDLER                                                                        push   cs                                                                      pop    es                                                                      mov    di, offset default.sub.-- low.sub.-- battery.sub.-- alarm               int    TASKINT                                                                 jmp    oem.sub.-- pm.sub.-- defaults                                           power.sub.-- management.sub.-- init endp                                       ;==================================================                            ;   Start Power Management . . .                                               ;==================================================                            ;                                                                              ;   After Initial Power Up Self Tests are completed,                           ;   power management is enabled. Do not enable until                           ;   it is time to boot the system.                                             ;                                                                              ;                                                                              power.sub.-- management.sub.-- enable proc                                     push   ds                                                                      call   get.sub.-- pm.sub.-- ds   ;load ds pointer                              or     pm.sub.-- flags, PM.sub.-- ENABLED                                      pop    ds                                                                      ret                                                                            power.sub.-- management.sub.-- enable endp                                     ;==================================================                            ;   Power Management dispatch routine                                          ;==================================================                            ;                                                                              ;   Programmatic interface to the Power Management Kernel.                     ;   used to read /alter management parameters.                                 ;                                                                              ;   This function is installed as Int 15h (task management)                    ;   function OCFh.                                                             Power.sub.-- Management proc near                                              sti                                                                            cmp    al, PM.sub.-- OEM.sub.-- FX                                                                      ;extended function??                                  jnz    @F                ;no . . .                                             jmp    oem.sub.-- pm.sub.-- extensions                                                                  ;do private functions                                 @@:    cmp    al,pwrmgt.sub.-- fx.sub.-- table.sub.-- len                      jae    md.sub.-- err     ;not here                                             push   ds                                                                      push   es                                                                      pusha                                                                          mov    bp,sp             ;stack addressing . . .                               call   get.sub.-- pm.sub.-- ds                                                                          ;load ds pointer                                      sub    ah,ah                                                                   shl    ax,1                                                                    mov    si,ax                                                                   call   pwrmgt.sub.-- fx.sub.-- table si!                                                                ;execute the function                                 popa                                                                           pop    es                                                                      pop    ds                                                                      retf   2                 ;return                                               md.sub.-- err:                                                                        mov    ah,86h         ;fx err                                           stc                                                                            retf   2                 ;save flags                                           Power.sub.-- Management endp                                                   page                                                                           ;==================================================                            ;   pm.sub.-- get.sub.-- profile                                               ;==================================================                            ;                                                                              ;   Return to caller the current active profile.                               ;   This may have been modified by Set profile calls.                          ;                                                                              pm.sub.-- get.sub.-- profile:                                                  dbMESSAGE fTEST8+fTESTb <pm.sub.-- get.sub.-- profile>                         mov    ax,on.sub.-- power.sub.-- status                                        mov    si.sub.-- arg, ax                                                       mov    ax,sleep.sub.-- power.sub.-- status                                     mov    di.sub.-- arg, ax                                                       mov    al,lb.sub.-- def.sub.-- event.sub.-- type                               mov    bl.sub.-- arg, al                                                       mov    al,kbd.sub.-- timeout                                                   mov    bh.sub.-- arg, al                                                       mov    al,doze.sub.-- timeout                                                  mov    cl.sub.-- arg, al                                                       mov    al,sleep.sub.-- timeout                                                 mov    ch.sub.-- arg, al                                                       mov    ax,pwr.sub.-- off.sub.-- timeout                                        mov    dx.sub.-- arg, ax                                                       clc                                                                            ret                                                                            ;==================================================                            ;   pm.sub.-- set.sub.-- profile                                               ;==================================================                            ;                                                                              ;   Set the current active profile.                                            ;   Alter the desired parameters. Do this by calling                           ;   get profile, and then changing just those parameters                       ;   and then calling set profile                                               pm.sub.-- set.sub.-- profile:                                                  dbMESSAGE fTEST8+fTESTb <pm.sub.-- set.sub.-- profile>                         mov    doze.sub.-- timeout, cl                                                 mov    sleep.sub.-- timeout, ch                                                mov    lb.sub.-- def.sub.-- event.sub.-- type, bl                              mov    kbd.sub.-- timeout, bh                                                  mov    pwr.sub.-- off.sub.-- timeout, dx                                       mov    pwr.sub.-- off.sub.-- count,0                                                                    ;clear countdown                                      mov    ax, si.sub.-- arg                                                       mov    on.sub.-- power.sub.-- status, ax                                       mov    ax, di.sub.-- arg                                                       mov    sleep.sub.-- power.sub.-- status, ax                                    mov    ax, si.sub.-- arg                                                       call   oem.sub.-- pm.sub.-- turn.sub.-- on.sub.-- peripherals                  clc                                                                            ret                                                                            page                                                                           ;==================================================                            ;   pm.sub.-- get.sub.-- rtc.sub.-- profile                                    ;==================================================                            ;                                                                              ;   Read Back current profile stored in the NV-RAM.                            ;   This profile is the default active at power up                             ;                                                                              pm.sub.-- get.sub.-- rtc.sub.-- profile:                                       dbMESSAGE fTEST8+fTESTb <pm.sub.-- get.sub.-- rtc.sub.-- profile>              mov    ah,CM.sub.-- OPCW                                                       call   rd.sub.-- rtcw                                                          mov    si.sub.-- arg, bx                                                       mov    ah,CM.sub.-- SPCW                                                       call   rd.sub.-- rtcw                                                          mov    di.sub.-- arg, bx                                                       mov    ah,CM.sub.-- DOZE                                                       call   rd.sub.-- rtcw                                                          mov    cx.sub.-- arg, bx                                                       mov    ah,CM.sub.-- ALM.sub.-- REP                                             call   rd.sub.-- rtcw                                                          mov    dx.sub.-- arg, bx                                                       mov    ah,CM.sub.-- DEF.sub.-- ALM                                             call   rd.sub.-- rtcw                                                          mov    bx.sub.-- arg, bx                                                       clc                                                                            ret                                                                            ;==================================================                            ;   pm.sub.-- set.sub.-- rtc.sub.-- profile                                    ;==================================================                            ;                                                                              ;   Set the current NV-RAM profile.                                            ;   Alter the desired parameters. Do this by calling                           ;   get rtc profile, and then changing just those parameters                   ;   and then calling set rtc profile                                           ;   This profile will be active next hard reset . . .                          pm.sub.-- set.sub.-- rtc.sub.-- profile:                                       dbMESSAGE fTEST8+fTESTb <pm.sub.-- set.sub.-- rtc.sub.-- profile>              mov    ah, CM.sub.-- OPCW                                                      mov    bx, si.sub.-- arg                                                       call   wr.sub.-- rtcw                                                          mov    ah, CM.sub.-- SPCW                                                      mov    bx, di.sub.-- arg                                                       call   wr.sub.-- rtcw                                                          mov    ah,CM.sub.-- DOZE                                                       mov    bx, cx.sub.-- arg                                                       call   wr.sub.-- rtcw                                                          mov    ah,CM.sub.-- ALM.sub.-- REP                                             mov    bx, dx.sub.-- arg                                                       call   wr.sub.-- rtcw                                                          mov    ah,CM.sub.-- DEF.sub.-- ALM                                             mov    bx, bx.sub.-- arg                                                       call   wr.sub.-- rtcw                                                          clc                                                                            ret                                                                            page                                                                           ;==================================================                            ;   pm.sub.-- event.sub.-- handler                                             ;==================================================                            ;                                                                              ;   Install a Low Battery Event Handler.                                       ;   Specify the Event criteria, which dictates                                 ;   under which conditions the Event Handler is called,                        ;   and specify a repeat rate for recurring conditions.                        ;   Also specify a power off/ Suspend timeout                                  ;   after the detection of a Low, Low Battery condition                        pm.sub.-- event.sub.-- handler:                                                dbMESSAGE fTEST8+fTESTb <pm.sub.-- event.sub.-- handler>                       xchg    lb.sub.-- event.sub.-- mask!,bx                                        mov    bx.sub.-- arg, bx                                                       xchg   word ptr  lb.sub.-- event.sub.-- handler!,di                            mov    di.sub.-- arg, di                                                       mov    bx,es.sub.-- arg                                                        xchg   word ptr  lb.sub.-- event.sub.-- handler+2!,bx                          mov    es.sub.-- arg, bx                                                       xchg    lb.sub.-- event.sub.-- rep!, cl                                        mov    cl.sub.-- arg, cl                                                       xchg    pwr.sub.-- off.sub.-- timeout!, dx                                     mov    dx.sub.-- arg, dx                                                       and     pm.sub.-- flags!,not PM.sub.-- LB.sub.-- HANDLER                       mov    ax, word ptr  lb.sub.-- event.sub.-- handler!                           or     ax, word ptr  lb.sub.-- event.sub.-- handler+2!                         jz     @F                                                                      or      pm.sub.-- flags!,PM.sub.-- LB.sub.-- HANDLER                           @@:    mov  lb.sub.-- event.sub.-- count!, 0                                                            ;time to do . . .                                     clc                                                                            ret                                                                            ;==================================================                            ;   pm.sub.-- one.sub.-- shot.sub.-- event.sub.-- handler                      ;==================================================                            ;                                                                              ;   Certain applications and/or management functions                           ;   may wish to be notified if a timeout period occurs                         ;   after a certain event. This function provides                              ;   a 55 Msec resolution timing function for timing                            ;   events, and acts like a hardware one-shot; timing out                      ;   calling the one shot handler, and cancelling the                           ;   timer until it is reloaded again.                                          pm.sub.-- one.sub.-- shot.sub.-- event.sub.-- handler:                         dbMESSAGE fTEST8+fTESTb <pm.sub.-- one.sub.-- shot.sub.-- handler>             mov    word ptr  one.sub.-- shot.sub.-- handler!,di                            mov    bx,es.sub.-- arg                                                        mov    word ptr  one.sub.-- shot.sub.-- handler+2!,bx                          mov    word ptr  one.sub.-- shot.sub.-- timer!, cx                             mov    word ptr  one.sub.-- shot.sub.-- timer+2!, dx                           mov    al,  pm.sub.-- flags!                                                                            ;get status                                           or     cx, dx            ;cancel??                                             jz     os.sub.-- cancel  ;yes . . .                                            ;==== Not a Cancel request, so check if one shot is rolling                    test   al, PM.sub.-- ONE.sub.-- SHOT.sub.-- HANDLER                            jnz    os.sub.-- err                                                           and    al, not PM.sub.-- ONE.sub.-- SHOT.sub.-- HANDLER                        mov    bx, word ptr  one.sub.-- shot.sub.-- handler!                           or     bx, word ptr  one.sub.-- shot.sub.-- handler+2!                         jz     @F                                                                      or     al, PM.sub.-- ONE.sub.-- SHOT.sub.-- HANDLER                            @@:    mov     pm.sub.-- flags!, al                                            clc                                                                            ret                                                                            os.sub.-- err:                                                                        mov    ah.sub.-- arg,86h                                                                             ;already active                                   stc                                                                            ret                                                                            os.sub.-- cancel:                                                              and    al, not PM.sub.-- ONE.sub.-- SHOT.sub.-- HANDLER                        mov     pm.sub.-- flags!, al                                                   clc                                                                            ret                                                                            ;==================================================                            ;   pm.sub.-- get.sub.-- pm.sub.-- status                                      ;==================================================                            ;                                                                              ;   Return the status of the System Status port.                               ;   this port has two defined bits:                                            ;                                                                              ;    bit 0 = Low Battery                                                       ;    bit 1 = Low, Low Battery                                                  ;                                                                              ;   Other bits have OEM specific meanings                                      pm.sub.-- get.sub.-- pm.sub.-- status:                                         dbMESSAGE fTEST8+fTESTb <pm.sub.-- get.sub.-- pm.sub.-- status>                call   oem.sub.-- pm.sub.-- get.sub.-- status                                  mov    bx.sub.-- arg, ax                                                       ret                                                                            ;==================================================                            ;   pm.sub.-- enter.sub.-- sleep                                               ;==================================================                            ;                                                                              ;   This function sets up a sleep command at the                               ;   next timer interrupt.                                                      ;                                                                              pm.sub.-- enter.sub.-- sleep:                                                  or     pm.sub.-- flags, PM.sub.-- SLEEP                                                                 ;say to sleep                                         ret                                                                            assume cs:code,ds:data0,es:pmdata                                              ;==================================================                            ;   read.sub.-- crt.sub.-- reg                                                 ;==================================================                            ;                                                                              ;   This routine is used to read the state of a                                ;   video register                                                             ;                                                                              ;                                                                              ;   inputs:  bl     = address in 6845                                          ;                                                                              ;   outputs: ax     = word read                                                ;==================================================                            read.sub.-- crt.sub.-- reg proc near                                           mov    dx,crt.sub.-- addr                                                                               ;set addr                                             mov    al,bl                                                                   out    dx,al                                                                   inc    dl                                                                      in     al,dx                                                                   mov    ch,al             ;get msb                                              dec    dl                                                                      mov    al,bl             ;set next addr                                        inc    al                                                                      out    dx,al                                                                   inc    dl                                                                      in     al,dx                                                                   mov    ah,ch             ;get lsb                                              ret                                                                            read.sub.-- crt.sub.-- reg                                                              endp                                                                  ;==================================================                            ;   read.sub.-- com                                                            ;==================================================                            ;                                                                              ;   This routine is used to read the status of a                               ;   8250 serial port and save it in memory                                     read.sub.-- com                                                                         proc            ;save com port in DX                                  add    dl,lcr                                                                  in     al,dx                                                                   or     al,DLAB           ;set dlab to read div reg                             jmp    $+2                                                                     out    dx,al                                                                   sub    dl,lcr                                                                  in     ax,dx             ;read divisor reg                                     stosw                                                                          add    dl,lcr                                                                  in     al,dx                                                                   and    al,not DLAB                                                             jmp    $+2                                                                     out    dx,al                                                                   sub    dl,lcr-ier                                                              mov    cx,6                                                                    rcom1: in    al,dx                                                             inc    dx                                                                      stosb                                                                          loop   rcom1                                                                   ret                                                                            read.sub.-- com                                                                         endp                                                                  ;==================================================                            ;   read.sub.-- lpt                                                            ;==================================================                            ;                                                                              ;   This routine is used to read the status of a                               ;   Industry Standard Parallel port and save it in memory                      read.sub.-- lpt                                                                         proc                                                                  add    dl,printer.sub.-- control                                               in     al,dx                                                                   stosb                                                                          ret                                                                            read.sub.-- lpt                                                                         endp                                                                  assume cs:code,ds:pmdata,es:data0                                              ;==================================================                            ;   write.sub.-- com                                                           ;==================================================                            ;                                                                              ;   This routine is used to restore the status of a                            ;   8250 serial port from where it was saved in memory                         write.sub.-- com proc                                                          add    dl,lcr                                                                  in     al,dx                                                                   or     al,DLAB                                                                 jmp    $+2                                                                     out    dx,al                                                                   sub    dl,lcr                                                                  lodsw                                                                          out    dx,ax                                                                   add    dl,lcr                                                                  in     al,dx                                                                   and    al,not DLAB                                                             jmp    $+2                                                                     out    dx,al                                                                   sub    dl,lcr-ier                                                              mov    cx,6                                                                    wcom1: lodsb                                                                   out    dx,al                                                                   inc    dx                                                                      loop   wcom1                                                                   ret                                                                            write.sub.-- com                                                                        endp                                                                  ;==================================================                            ;   write.sub.-- lpt                                                           ;==================================================                            ;                                                                              ;   This routine is used to restore the status of a                            ;   Industry Standard Parallel port from                                       ;   where it was saved in memory                                               write.sub.-- lpt                                                                        proc                                                                  add    dl,printer.sub.-- control                                               lodsb                                                                          out    dx,al                                                                   ret                                                                            write.sub.-- lpt                                                                        endp                                                                  ;==================================================                            ;   write crt register                                                         ;                                                                              ;   This routine is used to restore the status of a                            ;   video register from memory                                                 ;                                                                              ;   inputs:  cx     = word to write                                            ;            bl     = address in 6845                                          ;==================================================                            write.sub.-- crt.sub.-- reg proc near                                          mov    dx,crt.sub.-- addr                                                                               ;set addr                                             mov    al,bl                                                                   out    dx,al                                                                   mov    al,ch             ;send msb                                             inc    dl                                                                      out    dx,al                                                                   dec    dl                                                                      mov    al,bl             ;set next addr                                        inc    al                                                                      out    dx,al                                                                   inc    dl                                                                      mov    al,cl             ;send lsb                                             out    dx,al                                                                   ret                                                                            write.sub.-- crt.sub.-- reg endp                                               assume cs:code,ds:pmdata,es:nothing                                            page                                                                           ;==================================================                            ;   pm.sub.-- kbd.sub.-- hook                                                  ;==================================================                            ;                                                                              ;   In Software Based Power Management, this routine                           ;   is part of the Keyboard Interrupt chain. It is                             ;   used to detect keyboard activity.                                          ;                                                                              ;   Called every KBD INT: Set Keyboard Active bit                              ;                                                                              ;   restore video if necessary                                                 ;                                                                              ;   must save regs, take care of ints . . .                                    ;                                                                              ;                                                                              pm.sub.-- kbd.sub.-- hook:                                                     dbPC   fTEST1+fTESTb "k"                                                       call   get.sub.-- pm.sub.-- ds                                                                          ;get ds                                               test   pm.sub.-- flags, PM.sub.-- VBLANK                                                                ;video blanked out???                                 jz     @F                                                                      call   oem.sub.-- pm.sub.-- restore.sub.-- video                                                        ;turn on screen                                       and    pm.sub.-- flags, not PM.sub.-- VBLANK                                                            ;clear blank flag                                     @@:    or    pm.sub.-- flags, PM.sub.-- KBDACT                                                                ;say keyboard had                               activity                                                                       ret                                                                            page                                                                           ;==================================================                            ;   pm.sub.-- timer.sub.-- hook                                                ;==================================================                            ;                                                                              ;   In Software Based Power Management, this routine                           ;   performs the function of the Timer and Dispatcher                          ;   It is part of the Timer Interrupt chain, after                             ;   the timer end of interrupt (EOI) has been sent.                            ;                                                                              ;   Checks for system activity and DOZEs/ SLEEPs                               ;                                                                              ;   Entry conditions: cli, ds,es,pusha saved, ds=data0p                        ;                                                                              ;   This routine contains two threads of code,                                 ;   which execute independently.                                               ;                                                                              ;                                                                              ;   COUNTER thread:                                                            ;                                                                              ;                                                                              ;                                                                              ;   The COUNTER thread checks for the one shot,                                ;   handles the second and minute counters, and looks                          ;   at the low battery level, and dispatches the LB                            ;   event handler. It then looks at the DOZE flag,                             ;   and if doze is active, returns without changing                            ;   the activity status; so that the code after the DOZE                       ;   HLT can function.                                                          ;                                                                              ;                                                                              ;   DOZE thread:                                                               ;                                                                              ;                                                                              ;                                                                              ;   The DOZE thread runs when an activity check                                ;   shows no activity has been present for the                                 ;   entire DOZE timeout. The processor clock                                   ;   is slowed, the DOZE bit is set, interrupts                                 ;   are enabled, and the CPU is put into HLT.                                  ;   When HLT is exited, (18.2 hz) the activity                                 ;   status is checked, to see if DOZE should be                                ;   terminated. If activity is present,                                        ;   the DOZE flag is cleared and the                                           ;   activity exit is taken.                                                    ;                                                                              ;   If activity is not present, a test is made                                 ;   for the SLEEP timeout. If the SLEEP timeout                                ;   has elapsed, SLEEP is entered, after saving                                ;   the peripheral state. Otherwise, the CPU                                   ;   is halted, and the DOZE loop is reentered,                                 ;   and the cycle continues until                                              ;   terminated by ACTIVITY or SLEEP.                                           ;                                                                              ;==================================================                            even                 ;fast . . .                                               pm.sub.-- timer.sub.-- hook:                                                   cli                      ;ints are off . . .                                   call   get.sub.-- pm.sub.-- ds                                                                          ;establish ds                                         test   pm.sub.-- flags, PM.sub.-- ENABLED                                                               ;running yet??                                        jnz    @F                                                                      jmp    exit.sub.-- wo.sub.-- change                                                                     ;no . . .                                             @@:    call oem.sub.-- pm.sub.-- get.sub.-- hw                                                            ;get hw.sub.-- caps to                              ES:DI                                                                          test   pm.sub.-- flags, PM.sub.-- ONE.sub.-- SHOT.sub.-- HANDLER                                             ;have one??                                      jz     ck.sub.-- sec          ;no . . .                                        dec    word ptr one.sub.-- shot.sub.-- timer                                   sbb    word ptr one.sub.-- shot.sub.-- timer,0                                 jnz    ck.sub.-- sec                                                           and    pm.sub.-- flags, not PM.sub.-- ONE.sub.-- SHOT.sub.-- HANDLER                                          ;dont any                                       more . . .                                                                     call   one.sub.-- shot.sub.-- handler                                                                   ;called w/ ints disabled                              ;==================================================                            ;   First, handle the one second dispatching                                   ;==================================================                            even                                                                           ck.sub.-- sec:                                                                 dec    second.sub.-- counter                                                   jz     is.sub.-- sec                                                           jmp    exit.sub.-- wo.sub.-- change                                            ;==================================================                            ;   Second Rolled, Check Minutes                                               ;==================================================                            is.sub.-- sec:                                                                        mov second.sub.-- counter,18                                                                     ;ticks per second . . . reset                         dbPC   fTEST2+fTESTb " Q"                                                      dec    minute.sub.-- counter                                                                            ;count minutes . . .                                  jz     @f                                                                      jmp    not.sub.-- minute                                                       @@:    dbPC fTEST2+fTESTb "("                                                  page                                                                           ;==================================================                            ;   All Code Below is executed once per Minute.                                ;   All Minute Counters are decremented here . . .                             ;==================================================                            mov    minute.sub.-- counter, 60                                                                        ;reset                                                ;==================================================                            ;   Count Down Sleep Timer                                                     ;==================================================                            ;                                                                              ;   Turned On by Entering Doze . . .                                           sub    ax, ax            ;for resetting                                        cmp    sleep.sub.-- timeout,al                                                                          ;timeout used??                                       jz     lb.sub.-- dec     ;NO                                                   mov    al, sleep.sub.-- count                                                                           ;get sleep counter                                    test   al,al                                                                   jz     @F                                                                      dec    al                ;dec sleep counter                                    @@:    mov    sleep.sub.-- count, al                                                                          ;reset                                          ;==================================================                            ;   Count Down low battery event Timer                                         ;==================================================                            ;                                                                              ;   Rep count set by LB event detection                                        lb.sub.-- dec:                                                                 cmp    lb.sub.-- event.sub.-- rep,ah                                                                    ;timeout used??                                       jz     kbd.sub.-- dec    ;NO                                                   mov    al, lb.sub.-- event.sub.-- count                                                                 ;dec event counter                                    test   al, al            ;already 0???                                         jz     @F                ;yes . . .                                            dec    al                ;dec rep counter                                      @@:    mov    lb.sub.-- event.sub.-- count, al                                                                ;reset                                          ;==================================================                            ;   Check For Keyboard Activity                                                ;==================================================                            even                                                                           kbd.sub.-- dec:                                                                test   es: di!.HW.sub.-- CAPS, HWC.sub.-- KBACT                                jz     pwr.sub.-- dec    ;doesnt support KB activity                           call   oem.sub.-- pm.sub.-- kbd.sub.-- activity?                                                        ;kbd active??                                         jnz    nokbact           ;yes, normal                                          dbPC   fTEST2+fTESTb " Y"                                                      ;==================================================                            ;   Count Down Keyboard Timer                                                  ;==================================================                            ;                                                                              ;   Turned On by No Kbd Activity . . .                                         cmp    kbd.sub.-- timeout,0                                                                             ;timeout used??                                       jz     pwr.sub.-- dec    ;NO                                                   mov    al, kbd.sub.-- count                                                                             ;get blank counter                                    test   al,al             ;done . . .                                           jz     pwr.sub.-- dec                                                          dec    al                ;dec sleep counter                                    mov    kbd.sub.-- count, al                                                                             ;reset to 0                                           jnz    pwr.sub.-- dec    ;next counter                                         or     pm.sub.-- flags, PM.sub.-- VBLANK                                                                ;say its off . . .                                    call   oem.sub.-- pm.sub.-- blank.sub.-- video                                                          ;blank the video                                      jmp    short pwr.sub.-- dec                                                    nokbact:                                                                       mov    al,kbd.sub.-- timeout                                                                            ;reset counter                                        mov    kbd.sub.-- count, al                                                    call   oem.sub.-- pm.sub.-- reset.sub.-- kbd.sub.-- activity                                            ;clear activity bit                                   ;==================================================                            ;   Count Down Power Off Timer                                                 ;==================================================                            ;                                                                              ;   Turned On by LB2 detection below, and powers off                           ;   if hw supports it                                                          ;                                                                              even                                                                           pwr.sub.-- dec:                                                                test   es: di!.HW.sub.-- CAPS, HWC.sub.-- POWER                                jz     not.sub.-- po     ;doesnt support power off                             cmp    pwr.sub.-- off.sub.-- timeout,0                                                                  ;Countdown enabled??                                  jz     not.sub.-- po     ;NO                                                   dec    pwr.sub.-- off.sub.-- count                                                                      ;dec event counter                                    jnz    not.sub.-- po                                                           dbPC   fTEST2+fTESTb "p"                                                       call   oem.sub.-- pm.sub.-- power.sub.-- off                                   not.sub.-- po:                                                                 dbPC   fTEST2+fTESTb `)`                                                       page                                                                           ;==================================================                            ;   All Code Below is execute once a Second                                    ;==================================================                            even                                                                           not.sub.-- minute:                                                             ;==================================================                            ;   Check and attend to the low battery indicators . . .                       ;==================================================                            ;                                                                              ;   Once a Second, we check the Battery Levels via                             ;   polling. Since some hardware generates an NMI,                             ;   we may not need to do this, Since the NMI will                             ;   be invoked at event time.                                                  ;                                                                              ;   The Event Handler is assumed not to be re-entrant,                         ;   so it will not be re-entered until the first event                         ;   is handled. The next event will trigger as soon as                         ;   the PM.sub.-- IN.sub.-- LB.sub.-- HANDLER flag is cleared.                 ;                                                                              ;   Handler or no, the power off/Suspend Timeout is started                    ;   at Low, Low Battery detection.                                             test   es: di!.HW.sub.-- CAPS, HWC.sub.-- LB.sub.-- NMI                        jnz    ck.sub.-- led   ;supports nmi, dont need this                           call   oem.sub.-- pm.sub.-- get.sub.-- status                                                           ;get this stuff                                       and    ax, lb.sub.-- event.sub.-- mask                                                                  ;need to attend to??                                  jz     ck.sub.-- lb      ;no . . .                                             test   pm.sub.-- flags, PM.sub.-- LB.sub.-- HANDLER                                                       ;have one??                                         jnz    ck.sub.-- ilbh      ;yes . . .                                          ck.sub.-- lb:                                                                         mov    lb.sub.-- event.sub.-- count, 0                                                               ;clear rep count for re-                          entry . . .                                                                    ck.sub.-- lba:                                                                        test   ax, LBE.sub.-- LB2                                                                            ;need to start power                              off??                                                                          jz     ck.sub.-- led     ;no . . .                                             jmp    short pwr.sub.-- ct                                                                              ;still count power off                                ck.sub.-- ilbh:                                                                dbPC   fTEST2+fTESTb "v"                                                       test   pm.sub.-- flags, PM.sub.-- IN.sub.-- LB.sub.-- HANDLER                                              ;Blocked??                                         jnz    ck.sub.-- lb2        ;dont reenter                                      cmp    ax, lb.sub.-- last.sub.-- event                                                                  ;same event as previously??                           jnz    ck.sub.-- fevt                                                          cmp    lb.sub.-- event.sub.-- count,0                                                                   ;time to repeat??                                     jnz    ck.sub.-- lb2     ;no . . .                                             even                                                                           ck.sub.-- fevt:                                                                mov    lb.sub.-- last.sub.-- event,ax                                                                   ;save event                                           or     pm.sub.-- flags, PM.sub.-- IN.sub.-- LB.sub.-- HANDLER                  mov    bl,lb.sub.-- def.sub.-- event.sub.-- type                                                        ;default criteria                                     push   ax                                                                      call   lb.sub.-- event.sub.-- handler                                                                   ;do it, LB flags in                                   ax . . .                                                                       pop    ax                                                                      mov    bl, lb.sub.-- event.sub.-- rep                                                                   ;reset                                                mov    lb.sub.-- event.sub.-- count, bl                                                                 ;event rep time                                       and    pm.sub.-- flags, not PM.sub.-- IN.sub.-- LB.sub.-- HANDLER              ;==================================================                            ;   Start power off timeout/suspend machine                                    ;==================================================                            ck.sub.-- lb2:                                                                        test ax, LBE.sub.-- LB2                                                                          ;need to start power                                  off??                                                                          jz     ck.sub.-- led     ;no . . .                                             cmp    pwr.sub.-- off.sub.-- count,0                                                                    ;started previously??                                 jnz    ck.sub.-- led     ;yes . . .                                            pwr.sub.-- ct:                                                                        mov    ax, pwr.sub.-- off.sub.-- timeout                                                             ;start event                                      test   ax,ax             ;immediate off/suspend???                             jnz    pwr.sub.-- to     ;no . . .                                             test   es: di!.HW.sub.-- CAPS, HWC.sub.-- SUSPEND                              jz     ck.sub.-- led     ;doesnt support suspend                               dbPC   fTEST2+fTESTb "o"                                                       call   suspend           ;suspend the machine . . .                            jmp    exit.sub.-- w.sub.-- activity                                                                    ;yes, run now . . .                                   pwr.sub.-- to:                                                                        mov    pwr.sub.-- off.sub.-- count, ax                                                               ;counter                                          ;==================================================                            ;   Handle LED Flash Cycles                                                    ;==================================================                            ;                                                                              ;   Some OEMs flash LEDs at different duty cycles to                           ;   indicate different operational conditions.                                 ;                                                                              ;   On/Off modulation is provided by this function.                            ;                                                                              ;   LED flash cycles are handled                                               ;   during the once per second loop                                            ;                                                                              even                                                                           ck.sub.-- led:                                                                 test   es: di!.HW.sub.-- CAPS, HWC.sub.-- LEDS                                 jz     ck.sub.-- activity                                                                               ;doesnt support LEDs                                  cmp    led.sub.-- time.sub.-- on, 0                                                                     ;LED cycle active??                                   jz     ck.sub.-- activity                                                                               ;no                                                   dec    led.sub.-- next.sub.-- event                                                                     ;dec counter to next                                  delta                                                                          jnz    ck.sub.-- activity                                                                               ;Non-zero, wait                                       ;==== LED event time, toggle state, inc counters                               call   oem.sub.-- pm.sub.-- toggle.sub.-- led                                  mov    al, led.sub.-- time.sub.-- off                                                                   ;NO                                                   jz     ck.sub.-- led2                                                          mov    ax, led.sub.-- cycle.sub.-- count                                                                ;count infinite . . .                                 test   ax, ax            ;yes . . .                                            jz     ck.sub.-- led1                                                          dec    ax                                                                      mov    led.sub.-- cycle.sub.-- count, ax                                                                ;dec count every ON . . .                             jnz    ck.sub.-- led1    ;not timed out yet . . .                              mov    led.sub.-- time.sub.-- on, 0                                                                     ;LED cycle NOT active                                 ck.sub.-- led1:                                                                mov    al, led.sub.-- time.sub.-- on                                           ck.sub.-- led2:                                                                mov    led.sub.-- next.sub.-- event, al                                                                 ;reset                                                ;==================================================                            ;   Next, check if reentering from DOZE timer int                              ;==================================================                            ;                                                                              ;   Thread detection logic:                                                    ;   we made it to here, so lets see if we need to                              ;   exit to block again in DOZE, or to process a sleep                         ;   command, or perhaps enter doze.                                            ;                                                                              ;   If the DOZE flag is set, this means we entered the                         ;   timer hook from doze. we should then exit without                          ;   resetting the activity monitor, and let the DOZE thread                    ;   see if something happened to run Full Clock speed.                         ;                                                                              ;                                                                              ;   If the DOZE flag is not set, check and see if No activity                  ;   has been present for the DOZE timeout, and enter DOZE if so.               ;   Otherwise reset the activity monitor.                                          even                                                                       ck.sub.-- activity:                                                            test   pm.sub.-- flags; PM.sub.-- SLEEP                                                                 ;Req to sleep??                                       jz     @F                                                                      call   sleep             ;yes . . .                                            call   oem.sub.-- pm.sub.-- halt                                               jmp    wake              ;run . . .                                            @@:    test pm.sub.-- flags, PM.sub.-- DOZE                                                             ;Were WE dozing . . .                                 jz     @F                ;no                                                   jmp    exit.sub.-- wo.sub.-- change                                                                     ;YES, exit to code below                              ;==== Next, check the activity Monitor =====                                   @@:    dbPC fTEST2+fTESTb "I"                                                  call   oem.sub.-- pm.sub.-- activity?                                                                   ;turns ints off . . .                                 jnz    exit.sub.-- w.sub.-- activity                                                                    ;yes, normal                                          cmp    doze.sub.-- timeout, 0                                                                           ;doze allowed??                                       jz     @F                ;NO                                                   dec    doze.sub.-- count ;timeout??                                            jnz    @F                                                                      jmp    go.sub.-- doze                                                          @@:    sti                                                                     jmp    exit.sub.-- wo.sub.-- change                                            ;==================================================                            ;   exits . . .                                                                ;==================================================                            ;                                                                              ;   Various exits to the COUNTER and DOZE threads . . .                        ;                                                                              ;   Depending on Activity conditions                                               even                                                                       exit.sub.-- w.sub.-- activity:                                                 ;=== Exit, and reset the activity monitor                                      sti                                                                            mov    al, doze.sub.-- timeout                                                 mov    doze.sub.-- count, al                                                   ;=== Exit, and reset the activity monitor                                      exit.sub.-- w.sub.-- clear:                                                    dbPC   fTEST2+fTESTb " P"                                                      call   oem.sub.-- pm.sub.-- reset.sub.-- activity                              exit.sub.-- wo.sub.-- change:                                                  ret                                                                            page                                                                           ;==================================================                            ;   go.sub.-- doze                                                             ;==================================================                            ;                                                                              ;   At this point, we enter DOZE, having fulfilled the                         ;   criteria to enter that STATE                                               ;                                                                              even                                                                           go.sub.-- doze:                                                                mov    al, sleep.sub.-- timeout                                                                         ;start sleep counter                                  mov    sleep.sub.-- count, al                                                                           ;each time doze re-                                   entered                                                                        or     pm.sub.-- flags, PM.sub.-- DOZE                                                                  ;in doze                                              dbPC   fTEST2+fTESTb "d"                                                       slow.sub.-- cpu:                                                               call   oem.sub.-- pm.sub.-- halt                                                                        ;slow cpu, do halt                                    ;==== When we start up here, the sleep.sub.-- check will already               have                                                                           ;   been run and taken the early return                                        call   oem.sub.-- pm.sub.-- activity?                                          jz     ck.sub.-- sleep   ;no, chk sleep                                        and    pm.sub.-- flags, not PM.sub.-- DOZE                                                              ;clear doze flag                                      jmp    exit.sub.-- w.sub.-- activity                                                                    ;yes, normal                                          ;==================================================                            ;   Decrement Sleep Counters . . .                                             ;==================================================                            ;                                                                              ;   At this point, we enter check the SLEEP counters                           ;   for criteria to enter that STATE. If not, reenter                          ;   the DOZE loop                                                              ;                                                                              ck.sub.-- sleep:                                                               sub    al,al             ;register zero                                        cmp    sleep.sub.-- timeout,al                                                                          ;sleep allowed . . .                                  jz     slow.sub.-- cpu   ;NO                                                   cmp    sleep.sub.-- count,al                                                                            ;sleep time??                                         jnz    slow.sub.-- cpu   ;no                                                   call   sleep             ;enter sleep mode                                     and    pm.sub.-- flags, not PM.sub.-- DOZE                                                              ;clear doze flag                                      jmp    exit.sub.-- w.sub.-- activity                                                                    ;because we came out . . .                            page                                                                           ;==================================================                            ;   Sleep                                                                      ;==================================================                            ;                                                                              ;   At this point, we enter SLEEP, having fulfilled the                        ;   criteria to enter that STATE                                               ;                                                                              ;   Save, in order:                                                            ;   Video Adaptor state                                                        ;   LCD state                                                                  ;   8250 modes                                                                 ;   LPT modes                                                                  ;   Timer Mask                                                                 ;==================================================                            Sleep:                                                                         dbPC   fTEST2+fTESTb "S"                                                       push   di                                                                      push   si                                                                      push   cx                                                                      mov    di,offset sleep.sub.-- save.sub.-- buf                                  cld                                                                            and    pm.sub.-- flags, not PM.sub.-- SLEEP                                                             ;starting sleep req                                   assume cs:code,ds:data0,es:pmdata                                              push   ds                                                                      pop    es                                                                      mov    ds,data0p                                                               ;==================================================                            ;   save Display State                                                         ;==================================================                            call   oem.sub.-- pm.sub.-- save.sub.-- video.sub.-- state                     ;==================================================                            ;   save COM, LPT setups                                                       ;==================================================                            mov    dx, COM1          ;get COM1                                                    call read.sub.-- com                                                    mov    dx, COM2          ;get COM2                                             call   read.sub.-- com                                                         mov    dx, LPT1          ;get LPT1                                             call   read.sub.-- lpt                                                         mov    dx, LPT2                                                                call   read.sub.-- lpt                                                         mov    dx, LPT3                                                                call   read.sub.-- lpt                                                         call   oem.sub.-- pm.sub.-- save.sub.-- peripherals                                                     ;for private stuff . . .                              sleep.sub.-- cpu:                                                              in     al, PIC1          ;get timer mask                                       stosb                ;save                                                     or     al, TMRINT                                                              out    PIC1,al           ;disable the timer interrupt                          assume cs:code,ds:pmdata,es:data0                                              push   es                                                                      pop    ds                                                                      mov    es,data0p         ;swap ES/DS                                           mov    ax,sleep.sub.-- power.sub.-- status                                                              ;turns off stuff . . .                                call   oem.sub.-- pm.sub.-- turn.sub.-- off.sub.-- peripherals                                          ;actually turns off                                   stuff . . .                                                                    ret                                                                            page                                                                           wake:                                                                          ;===== Restore Peripheral Status =====                                         ;                                                                              ;   Because we are here, this means the wakeup key                             ;   was pressed, or an external interrupt came in.                             ;   Time to wake up . . .                                                      ;                                                                              ;                                                                              ;   Restore, in order:                                                         ;   Video Adaptor state                                                        ;   8250 mode                                                                  ;   LPT mode                                                                   ;   Timer Interrupt                                                            ;==================================================                            cli                                                                            mov    ax,on.sub.-- power.sub.-- status                                                                 ;What to turn on . . .                                call   oem.sub.-- pm.sub.-- turn.sub.-- on.sub.-- peripherals                                           ;go do it                                             mov    si,offset sleep.sub.-- save.sub.-- buf                                                           ;start of save area                                   cld                                                                            ;==================================================                            ;   Restore Display State                                                      ;==================================================                            call oem.sub.-- pm.sub.-- restore.sub.-- video.sub.-- state                    ;==================================================                            ;   restore COM and PRN                                                        ;==================================================                            mov    dx,COM1           ;get com port                                         call   write.sub.-- com                                                        mov    dx,COM2           ;get com port                                         call   write.sub.-- com                                                        mov    dx,LPT1           ;restore lpt port                                     call   write.sub.-- lpt                                                        mov    dx,LPT2           ;restore lpt port                                     call   write.sub.-- lpt                                                        mov    dx,LPT3           ;restore lpt port                                     call   write.sub.-- lpt                                                        call   oem.sub.-- pm.sub.-- restore.sub.-- peripherals                                                  ;for private stuff . . .                              push   ds                                                                      call   set.sub.-- ibm.sub.-- timer                                                                      ;restore ticks . . .                                  pop    ds                                                                      lodsb                                                                          out    PIC1,al           ;reenable interrupts                                  pop    cx                                                                      pop    si                                                                      pop    di                                                                      dbPC   fTEST2+fTESTb "G"                                                       ret                                                                            page                                                                           ;==================================================                            ;   suspend                                                                    ;==================================================                            ;                                                                              ;   Swap stacks, to                                                            ;                                                                              ;                                                                              assume cs:code,es:data0,ds:pmdata                                              suspend                                                                               proc                                                                    ;===== Save User Stack =====                                                   cli                                                                            mov    ax,ss                                                                   mov    pm.sub.-- save.sub.-- ss, ax ;save stack                                mov    ax,sp                                                                   mov    pm.sub.-- save.sub.-- sp, ax                                            sti                                                                            ;===== Run On Resume Stack =====                                               mov    ax, ds                                                                  mov    ss, ax            ;setup resume stack                                   mov    sp, offset pm.sub.-- resume.sub.-- stack                                mov    es,data0p                                                               mov    reset.sub.-- flag, FRESTORE                                             call   checksum          ;check this memory                                    mov    pm.sub.-- ram.sub.-- chksum, ax                                                                  ;save in pm.sub.-- datat                              call   sleep             ;save it all . . .                                    call   oem.sub.-- pm.sub.-- suspend                                                                     ;do it . . .                                          ;==================================================                            ;   pm.sub.-- resume                                                           ;==================================================                            ;                                                                              ;   Cold Boot code jmps here with BP as no resume                              ;   return address . . .                                                       ;                                                                              ;   check for a valid resume, do so                                            ;                                                                              ;   otherwise, jmp bp to cold boot code                                        resume:                                                                        mov    es,data0p                                                               cmp    reset.sub.-- flag, FRESTORE                                             jnz    resume.sub.-- err                                                       ;===== PM data should still be valid =====                                     call   get.sub.-- pm.sub.-- ds ;get datasg                                     mov    ax, ds                                                                  mov    ss, ax            ;setup resume stack                                   mov    sp, offset pm.sub.-- resume.sub.-- stack                                call   checksum                                                                cmp    ax, pm.sub.-- ram.sub.-- chksum                                         jnz    resume.sub.-- err                                                       call   wake              ;restore devices . . .                                ;===== Restore User Stack =====                                                mov    ax, pm.sub.-- save.sub.-- ss                                            mov    ss, ax                                                                  mov    sp, pm.sub.-- save.sub.-- sp                                            ret                      ;to suspend caller                                    resume.sub.-- err:                                                             jmp    bp                ;return to do a hard                                  reset                                                                          suspend                                                                               endp                                                                    code   ends                                                                    end                                                                            ______________________________________                                    

                  TABLE 2                                                          ______________________________________                                         Program Listing                                                                A computer program embodiment of the software monitor for                      the power management unit appears in the following TABLE 2.                    Do power management functions of int 16h and int 8h                            Copyright - 1990 Vadem, Inc.                                                   All Rights Reserved.                                                           C:                                                                             code   segment  public   'code'                                                assume   cs:code                                                               org    100h                                                                    start:                                                                         jmp    init                                                                    even                                                                           pp.sub.-- addr                                                                        dw    0378h                                                             old.sub.-- i8                                                                         label    dword                                                          i8.sub.-- off                                                                         dw    0                                                                 i8.sub.-- seg                                                                         dw    0ffffh                                                            old.sub.-- i10                                                                        label    dword                                                          i10.sub.-- off                                                                        dw    0      ; vector to old i10                                        i10.sub.-- seg                                                                        dw    0ffffh                                                            old.sub.-- i16                                                                        label    dword                                                          i16.sub.-- off                                                                        dw    0      ; vector to old i16                                        i16.sub.-- seg                                                                        dw    0ffffh                                                            sctr   db    0      ; counter for timeouts                                     two.sub.-- ctr                                                                        dw    12*182   ; 2 minute counter                                       ;---- Interrupt 10h handler                                                    new.sub.-- i10:                                                                call busy.sub.-- check                                                         jmp  old.sub.-- i10                                                            ;---- Interrupt 8 handler                                                      new.sub.-- i8:                                                                 call busy.sub.-- check                                                         jmp  old.sub.-- i8                                                             busy.sub.-- check:                                                             cmp    sctr,0   ; already in faxt mode?                                         jz    i8fast.sub.-- mode                                                      sub    sctr,50                                                                  jz    i8fast.sub.-- mode                                                       jnc   i8z                                                                     mov    sctr,0                                                                  ;---- Switch to turbo mode here|                                               i8fast.sub.-- mode:                                                            cmp    two.sub.-- ctr,0                                                                          ; if timed out, do nothing                                    jz    i8z        ; let IO monitor take over                                   ---- Two minutes have not gone by, turn it to ON|                              dec    two.sub.-- ctr                                                          push   dx                                                                      push   ax                                                                      mov    dx,0178h                                                                mov    al,0c0h                                                                 out    dx,al                                                                   inc    dx                                                                      in     al,dx      ; get status of chip                                         mov    ah,al                                                                   and    a1,3     ; LSB 2 bits                                                    jz    i8q      ; if not ON, nothing to do|                                    dec    dx                                                                      mov    al,0c0h                                                                 out    dx,al                                                                   inc    dx                                                                      mov    al,ah                                                                   and    al,not 3 ; set to ON mode                                               out    dx,al                                                                   i8q:                                                                           pop    ax                                                                      pop    dx                                                                      i8z:                                                                           ret                                                                            ;---- Interrupt 16 interceptor                                                 new.sub.-- i16:                                                                ----- Time to switch from ON to DOSE mode?                                     push   ax                                                                      push   dx                                                                      mov    dx,0178h                                                                mov    al,0c0h                                                                 out    dx,al                                                                   inc    dx                                                                      in     al,dx      ; get status of chip                                         mov    ah,al                                                                   and    al,3     ; LSB 2 bits                                                    jnz   i16.sub.-- dose                                                                         ; if not ON, nothing to do|                                    ;---Check to see if time to go into DOSE . . .                                 add    sctr,24                                                                  jnc   i16q                                                                    ;--- Time to go into DOZE|                                                     dec    dx                                                                      mov    al,0c0h                                                                 out    dx,al                                                                   inc    dx                                                                      mov    al,ah                                                                   or     al,1     ; set to dose mode                                             out    dx,al      ; we are now in DOSE mode|                                    jmp   short i16setctrs                                                        ;--- We are already in DOSE mode, count faster|                                i16.sub.-- dose:                                                               add    sctr,200                                                                 jnc   i16q                                                                    i16setctrs:                                                                    mov    sctr,0ffh  ; clamp it                                                   mov    two.sub.-- ctr,12 * 182                                                                     ; 18.2 Hz * 120 seconds                                    i16q:                                                                          pop    dx                                                                      pop    ax                                                                      jmp    old.sub.-- i16                                                                            ; do the original i16                                        init.sub.-- str                                                                         db     'Power management controller version 1.00.$'                   assume   ds:code                                                               init:                                                                          mov    dx,offset init.sub.-- str                                               mov    ah,9                                                                    int    21h                                                                     mov    ax,3508h                                                                int    21h                                                                     mov    i8.sub.-- seg,es                                                        mov    i8.sub.-- off,bx                                                        push   ds                                                                      pop    es                                                                      mov    dx,offset new.sub.-- i8                                                 mov    ax,2508h                                                                int    21h                                                                     mov    ax,3510h                                                                int    21h                                                                     mov    i10.sub.-- seg,es                                                       mov    i10.sub.-- off,bx                                                       push   ds                                                                      pop    es                                                                      mov    dx,offset new.sub.-- i10                                                mov    ax,2510h                                                                int    21h                                                                     mov    ax,3516h                                                                int    21h                                                                     mov    i16.sub.-- seg,es                                                       mov    i16.sub.-- off,bx                                                       push   ds                                                                      pop    es                                                                      mov    dx,offset new.sub.-- i16                                                mov    ax,2516h                                                                int    21h                                                                     mov    dx,offset init.sub.-- str+15                                            mov    cl,4                                                                    shr    dx,c1                                                                   mov    ax,3100h                                                                int    21h                                                                     code   ends                                                                    end    start                                                                   ______________________________________                                    

While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention. 

What is claimed is:
 1. A computer system having an activity level and a power consumption level and comprising a power management system and a plurality of computer system devices powered by a single common computer power supply, said plurality of computer system circuits including a CPU device, a plurality of input/output devices, a memory device, and a single common system bus which directly connects the CPU device with the input/output devices, wherein said power management system comprises:an activity monitor that monitors the activity level computer system and generates a first inactivity indicator after a first predetermined period of inactivity and a second inactivity indicator a second predetermined period of inactivity after generating the first inactivity indicator; a state controller that has three powered modes of operation including a first state, a second state, and a third state, said state controller being responsive to the activity monitor and transitions from said first state to said second state in response to said first inactivity indicator, and transitions from said second state to said third state in response to said second inactivity indicator; and a power switching circuit responsive to the state controller which couples said single computer power supply to a first predetermined group of the computer system devices when the state controller is in said first state, to a second predetermined group comprising fewer of the computer system devices than the first predetermined group when the state controller is in said second state, and to a third predetermined group comprising fewer of the computer system devices than the second predetermined group when the state controller is in said third state; said state controller generates a state control signal identifying the current operating state as one of said first state, said second state, and said third state; and wherein said power switching circuit further comprises:a first state power control circuit outputting a plurality of first state power control signals, each one of said plurality of signals being associated with at least one particular device, for directing power only to each of said first predetermined group of computer devices when operating in said first state; a second state power control circuit outputting a plurality of second state power control signals, each one of said plurality of signals being associated with at least one particular device, for directing power only to each of said second predetermined group of computer devices when operating in said second state; a third state power control circuit outputting a plurality of third state power control signals, each one of said plurality of signals being associated with at least one particular device, for directing power only to each of said third predetermined group of computer devices when operating in said third state; a power control signal multiplexer circuit receiving said plurality of first, second, and third state power control signals and selecting one particular plurality of power control signals to output from among said plurality of first, second, and third power control signals in response to said state control signal; and a plurality of switches, each said switch connected between said power supply and at least one of said computer system devices, for controlling coupling of power from said power supply to said connected computer system devices in response to said particular plurality of power control signals; whereby the power consumption level of the computer system is controlled in response to the activity level of the computer system.
 2. The computer system in claim 1, wherein:said first state power control circuit comprises a first register storing a plurality of bits, each said bit identifying a power ON/OFF condition for the associated computer system device when said computer system is operating in said first state; said second state power control circuit comprises a second register storing a plurality of bits, each said bit identifying a power ON/OFF condition for the associated computer system device when said computer system is operating in said second state; and said third state power control circuit comprises a third register storing a plurality of bits, each said bit identifying a power ON/OFF condition for the associated computer system device when said computer system is operating in said third state.
 3. The computer system in claim 2, wherein said first state comprises a DOZE state, said second state comprises a SLEEP state, and said third state comprises a SUSPEND state.
 4. The computer system in claim 1, wherein each of said plurality of switches comprises a transistor in the line supplying Vcc from said power supply to each of said connected device.
 5. The computer system in claim 1, wherein each of said input/output devices are connected to system bus by tristate logic.
 6. A computer system having an activity level and a power consumption level and comprising a power management system and a plurality of computer system devices powered by a single common computer power supply, said plurality of computer system circuits including a CPU device, a plurality of input/output devices, a memory device, and a single common system bus which directly connects the CPU device with the input/output devices, wherein said power management system comprises;an activity monitor that monitors the activity level of the computer system and generates a first inactivity indicator after a first predetermined period of inactivity and a second inactivity indicator a second predetermined period of inactivity after generating the first inactivity indicator; a state controller that has three powered modes of operation including a first state, a second state, and a third state, said state controller being responsive to the activity monitor and transitions from said first state to said second state in response to said first inactivity indicator, and transitions from said second state to said third state in response to said second inactivity indicator; and a power switching circuit responsive to the state controller which couples said single computer power supply to a first predetermined group of the computer system devices when the state controller is in said first state, to a second predetermined group comprising fewer of the computer system devices than the first predetermined group when the state controller is in said second state, and to a third predetermined group comprising fewer of the computer system devices than the second predetermined group when the state controller is in said third state; and wherein said activity monitor that monitors the activity level of the computer system further comprises:means for identifying each of a plurality of computer operational activities as either an active activity or an idle activity and for associating each of said plurality of activities with a predetermined activity value and with either a first arithmetic sign for activities identified as active activities or with a second arithmetic sign opposite to said first sign for activities identified as idle activities; and an activity count accumulator for accumulating an activity count upon the occurrence of each of a plurality of predefined activities including means for adding to a stored activity count, upon the occurrence of any one of said plurality of predefined activities, a predetermined activity value associated with said particular activity; and means for comparing the accumulated stored activity count with a conserve threshold and for causing said first inactivity indicator when said computer system is operating in said first state and said second inactivity indicator signal when said computer system is operating in said second state if the accumulated activity count has a predetermined algebraic relationship relative to the conserve threshold; and wherein said state controller is responsive to transition said powered state of operation from said first state to said second state when said computer system is operating in said first state, and to transition said powered state of operation from said second state to said third state when said computer system is operating in said second state; whereby the power consumption level of the computer system is controlled in response to the activity level of the computer system.
 7. The computer system in claim 6, wherein said computer system identifies at least one of said plurality of computer system devices by a device address communicated over said bus; and wherein said activity monitor further comprises:a memory configured for storing an address range data defining a particular range of device addresses; detector means, operatively coupled to said bus for monitoring address references communicated over said bus and to said memory for reading said stored address range data, and for comparing said address references with said address range data to generate an activity signal indicating that an address communicated over said bus was within the address range specified by one of said stored address range data; an activity timer, operatively coupled to said detector means to receive said activity signal if generated, and either: (i) in response to receipt of said activity signal within a first predetermined period of time, resetting said activity timer to a predetermined condition, and (ii) in response to failing to receive said activity signal within said first predetermined period of time, generating said first inactivity signal, and (iii) in response to failing to receive said activity signal within said second predetermined period of time, generating a said second inactivity signal; and wherein said state controller is operatively coupled to said activity timer to receive said first inactivity indicator signal and said second inactivity indicator signal and to said detector means to receive said activity signal, for controlling an operating condition of at least one of said computer system devices; said state controller controlling transition of said or each computer system device from a first state to a second state in response to receipt of said first inactivity indicator signal, controlling transition of said or each computer system device from a second state to said third state in response to receipt of said second inactivity indicator signal, and controlling transition of said or each computer system device from said second and said third state to said first state in response to receipt of said activity signal.
 8. A computer system having an activity level and a power consumption level and comprising a power management system and a plurality of computer system devices powered by a single common computer power supply, said plurality of computer system circuits including a CPU device, a plurality of input/output devices, a memory device, and a single common system bus which directly connects the CPU device with the input/output devices, wherein said power management system comprises:an activity monitor that monitors the activity level of the computer system and generates a first inactivity indicator after a first predetermined period of inactivity and a second inactivity indicator a second predetermined period of inactivity after generating the first inactivity indicator; a state controller that has three powered states of operation including a first state, a second state, and a third state, said state controller being responsive to the activity monitor and transitions from said first state to said second state in response to said first inactivity indicator, and transitions from said second state to said third state in response to said second inactivity indicator; and a power switching circuit responsive to the state controller which couples said single computer power supply to a first predetermined group of the computer system devices when the state controller is in said first state, to a second predetermined group comprising fewer of the computer system devices than the first predetermined group when the state controller is in said second state, and to a third predetermined group comprising fewer of the computer system devices than the second predetermined group when the state controller is in said third state; said state controller generates a state control signal identifying the current operating state as one of said first state, said second state, and said third state; and wherein said power switching circuit further comprises:a first state power control circuit outputting a plurality of first state power control signals, each one of said plurality of signals being associated with at least one particular device, for directing power only to each of said first predetermined group of computer devices when operating in said first state; a second state power control circuit outputting a plurality of second state power control signals, each one of said plurality of signals being associated with at least one particular device, for directing power only to each of said second predetermined group of computer devices when operating in said second state; a third state power control circuit outputting a plurality of third state power control signals, each one of said plurality of signals being associated with at least one particular device, for directing power only to each of said third predetermined group of computer devices when operating in said third state; a power control signal multiplexer circuit receiving said plurality of first, second, and third state power control signals and selecting one particular plurality of power control signals to output from among said plurality of first, second, and third power control signals in response to said state control signal; and a plurality of switches, each said switch connected between said power supply and at least one of said computer system devices, for controlling coupling of power from said power supply to said connected computer system devices in response to said particular plurality of power control signals; said first state power control circuit comprises a first register storing a plurality of bits, each said bit identifying a power ON/OFF condition for the associated computer system device when said computer system is operating in said first state; said second state power control circuit comprises a second register storing a plurality of bits, each said bit identifying a power ON/OFF condition for the associated computer system device when said computer system is operating in said second state; and said third state power control circuit comprises a third register storing a plurality of bits, each said bit identifying a power ON/OFF condition for the associated computer system device when said computer system is operating in said third state; and wherein said first state comprises a DOZE state, said second state comprises a SLEEP state, and said third state comprises a SUSPEND state; whereby the power consumption level of the computer system is controlled in response to the activity level of the computer system.
 9. A computer system having an activity level and a power consumption level and comprising a power management system and a plurality of computer system devices powered by a single common computer power supply and being responsive to receipt of at least one clock signal, said plurality of computer system circuits including a CPU device, a plurality of input/output devices, a memory device, and a single common system bus which directly connects the CPU device with the input/output devices, wherein said power management system comprises:an activity monitor that monitors the activity level of the computer system and generates a first inactivity indicator after a first predetermined period of inactivity and a second inactivity indicator a second predetermined period of inactivity after generating the first inactivity indicator; a state controller that has three powered modes of operation including a first state, a second state, and a third state, said state controller being responsive to the activity monitor and transitions from said first state to said second state in response to said first inactivity indicator, and transitions from said second state to said third state in response to said second inactivity indicator; a power switching circuit responsive to the state controller which couples device operating power from said single computer power supply to a first predetermined group of the computer system devices when the state controller is in said first state, to a second predetermined group comprising fewer of the computer system devices than the first predetermined group when the state controller is in said second state, and to a third predetermined group comprising fewer of the computer system devices than the second predetermined group when the state controller is in said third state; and a clock switching and control circuit, separate and operating independently from said power switching circuit, for reducing a frequency of said at least one clock signal communicated to said computer devices; whereby the power consumption level of the computer system is controlled in response to the activity level of the computer system.
 10. A method for operating a computer system having an activity level and a power consumption level and comprising a plurality of computer system circuits including a CPU, a plurality of input/output circuits, a memory circuit, and a common system bus which connects said CPU with said memory circuit and said input/output circuits, and having a plurality of functional power states, said plurality of computer system circuits configured to receive circuit operating power signal from a single common computer power supply and to receive an oscillating clock signal different from said operating power signal, wherein the method comprises the steps of:monitoring the activity level of the computer system and generating a first inactivity indicator after a first predetermined period of inactivity and a second inactivity indicator a second predetermined period of inactivity after generating the first inactivity indicator; switching the power state of the computer system from a first state to a second state in response to the first inactivity indicator; switching the power state of the computer system from the second state to a third state in response to the second inactivity indicator; coupling said circuit operating power signal from said common power supply and said clock signal at a first frequency to a first predetermined group of the computer system circuits when the computer system is in said first state; coupling said circuit operating power signal from said common power supply to a second predetermined group comprising fewer of the computer system circuits than the first predetermined group when the computer system is in said second state; coupling said clock signal at a second frequency lower than said first frequency to a predetermined group of said computer system circuits when the computer system is in said second state; coupling said circuit operating power signal from said common power supply to a third predetermined group comprising fewer of the computer system circuits than the second predetermined group when the computer system is in said third state; and said power consumption level of the computer system being automatically controlled by said computer system in response to the monitored activity level of the computer system.
 11. A computer system having an activity level and a power consumption level and comprising a power management system and a plurality of computer system devices powered by a single common computer power supply, said plurality of computer system circuits including a CPU device, a plurality of input/output devices, a memory device, and a single common system bus which directly connects the CPU device with the input/output devices, wherein said power management system comprises:an activity monitor that monitors the activity level of the computer system and generates a first inactivity indicator after a first predetermined period of inactivity and a second inactivity indicator a second predetermined period of inactivity after generating the first inactivity indicator; a state controller that has three powered modes of operation including a first state, a second state, and a third state, said state controller being responsive to the activity monitor and transitions from said first state to said second state in response to said first inactivity indicator, and transitions from said second state to said third state in response to said second inactivity indicator; and a power switching circuit responsive to the state controller which couples said single computer power supply to a first predetermined group of the computer system devices when the state controller is in said first state, to a second predetermined group comprising fewer of the computer system devices than the first predetermined group when the state controller is in said second state, and to a third predetermined group comprising fewer of the computer system devices than the second predetermined group when the state controller is in said third state; said state controller generating a state control signal identifying the current operating state as one of said first state, said second state, and said third state; and wherein said power switching circuit further comprises:a power control circuit generating a plurality of power control signals, each one of said plurality of power control signals being associated with at least one particular computer device; said power control circuit being responsive to said state control signal to generate said power control signals such that said operating power is directed only to each of said first predetermined group of computer devices when operating in said first state, only to each of said second predetermined group of computer devices when operating in said second state, and only to each of said third predetermined group of computer devices when operating in said third state; and a plurality of switches, each said switch connected between said power supply and at least one of said computer system devices, responsive to said power control signals for controlling coupling of said operating power from said power supply to said computer system devices in response to receipt of said plurality of power control signals; whereby the power consumption level of the computer system is controlled in response to the activity level of the computer system.
 12. The computer system in claim 11, wherein said computer devices comprise electronic circuits including transistors, and wherein said device operating power comprises a transistor bias supply voltage for said transistors. 